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Author Topic: Brennan Torpedo  (Read 68421 times)

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Offline Norma O Connor

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Re: Brennan Torpedo
« Reply #104 on: July 01, 2018, 00:00:25 »
Hi Kyn, 

I am so delighted to eventually be able to contact you through this wonderful educational forum!  My name is Norma O'Connor and I have spent a year working in Camden Fort Meagher, Crosshaven Co. Cork trying to compile and gather historical documents and update records for the fortification.   In essence to tell the story of Camden Fort Meagher formerly Fort Camden and Fort Meagher.  Along with working in the Fort I have gone back to college - UCC to do my MA in Digital Arts and Humanities.  My thesis is on Camden Fort Meagher.

I have created an online archive for Camden Fort Meagher and carried out 3D Scans & VR Walkthroughs  of specific areas within the Fort. and  They are working models and works in progress!  Enjoy :  )  As you know There is NO ON-SITE ACCESS AVAILABLE, OUT OF BOUNDS.   

I came across the Kent History Forum website: while researching information on Camden Fort Meagher.  I particularly like the history and photographic sections relating to Louis Brennan, Brennan Torpedo, Brennan Torpedo Factory Gillingham Kent, Royal Engineers Submarine Mining Depot - Chatham etc. 

Would it be possible please to link to and quote from your website as you have an important historical document and photographic record of Louis Brennan & the Brennan Torpedo including serving personnel? 

I would particularly like to include info links within the 3D Scan of the Brennan Torpedo:  I will credit you and / or your members accordingly.  This will help facilitate further research, learning and insights into our shared cultural and military history. 

Likewise you and your members are welcome to link to and Follow the Camden Fort Meagher Archives, 3D scans, VR Experiences and Photographic Narrative and contribute photos, videos and stories etc.   Also if you can put names, dates location etc. to any of the photos that would be great too. 
Please submit via Comments below photos. 

Looking forward to hearing from you :  )   

Kind Regards,

Norma O'Connor

Offline kyn

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Re: Brennan Torpedo
« Reply #103 on: January 01, 2015, 17:02:57 »
Submarine Mining School Gillingham Pier

9 Aug 1883


I have the honor to state that, in accordance with your verbal instructions of the 7th inst I visited Sheerness yesterday morning, and in company with Lt. Colonel Le Mesurier and Lieut. Friend inspected Garrison Point and the adjacent beach with a view of ascertaining if that locality would be suitable for the trials of my torpedo in the event of its been determined to operate it from shore.

This locality offers several sites from which the operations could be conducted, but after carefully examining these and consulting with the above named officers I am of opinion that the north end of the Gun Wharf is the most suitable for the following reasons. –

1.   It is screened by the Fort from the fire f an enemy until he is well within the range of the torpedo.

2.   It commands the whole width of the channel for a considerable distance in both directions.

3.   It is most probable that this site would be used for a permanent station.

4.   Two methods of launching could be demonstrated, showing how the launching could be effected in the one case from a wall firing vertically from the water and in the other from a shelving beach.

5.   The situation is secluded from the observation of the public.

6.   The existing arrangements of the Fort would not be interfered with.

7.   It is the opinion of Lt. Colonel Le Mesurier and Lieut. Friend that trials from this site would severely test the powers of the torpedo, as very very strong currents and eddies exist in the locality making it a difficult matter to manage ordinary boats and steam launches.

With reference to the alternative method of operating from shore by means of a locomotive engine running on rails parallel to the beach, so as to command several points.  To carry this act fully would necessitate works of much greater magnitude and cost than these required for a fixed station such as that proposed.  Whereas from the fixed stations a method of launching could be demonstrated similar to that which would be adopted in the case of the locomotive being used.

I have the honor to be
Your most obedient servant
Louis Brennan

Signed by: Colonel E. C. Gordon R.E. Commandant S.M.E.

Offline kyn

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Re: Brennan Torpedo
« Reply #102 on: August 07, 2014, 20:39:25 »
There are currently two forts interested at the moment, both of which would have them on display in time.  Once I know the arrangements I will let you know :)


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Re: Brennan Torpedo
« Reply #101 on: August 07, 2014, 09:10:33 »
Brilliant Kyn :)

Are there any plans to have them on display, or is all that yet to be decided/sorted out?

Offline kyn

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Re: Brennan Torpedo
« Reply #100 on: August 06, 2014, 15:40:47 »
I am currently arranging the re-homing of these rails, once in place at Cliffe Fort :)

Offline kyn

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Re: Brennan Torpedo
« Reply #99 on: July 10, 2014, 19:47:43 »

154.   A great number of factors affect the speed of a torpedo, and it is impossible, except with elaborate apparatus and under perfect conditions, to measure the speed with absolute accuracy.
The usual formulae, based on the number of revolutions of the propeller and an approximate mean slip, are, however, quite sufficiently accurate to be of great value.  It fails in absolute accuracy because the slip varies under different conditions, but this variation is very small compared with the actual variation of speed of the torpedo.
The very different speed results obtained from the formulae have led to the idea that the latter are so inaccurate as to be useless.  This is by no means the case, and if care is taken to compare the conditions of the various runs, and to obtain the necessary data for the formulae accurately, it will be found that the results are generally perfectly normal, and that the differences are actual differences of speed, due to the conditions of the runs.
All the conditions of a run which may affect the speed of a torpedo through the water should therefore be borne in mine when considering the speed obtained from formulae.
The causes of variation of speed are very numerous, and such points as bad depth, too high or low a stress, time of giving full speed, irregularities in propellers, heated bearings, &C., are obvious and need to reference.  Though such causes have to be taken into account in considering the speed results, it is from ordinary runs, where these should all be normal, that the most valuable information is obtained.
Some of the chief causes which affect the speed in such runs are:-

155.   Length if Run. – Directly owing to the amount of wire in the water.
Amount of Wire kept out of the Water. – Hence the height of universal pulleys, bollards, and so tide level.
Running in Curves. – Apart from possible variation of depth and slight extra rudder resistance, the speed may be considerably affected in both directions by curves.
If there is a considerable bight of wire in the water there will be less stress on the wire at the torpedo (even if the stress is kept up at the engine),as part of the power is expended in straightening up the bight through the water.  The speed, therefore, is diminished till the bight is taken up.
When once the bight is pulled straight, however, the torpedo is actually nearer the installation than would be the case wen the same amount of wire has been pulled out in a straight run; there is, therefore, less wire in the water, and the torpedo is consequently going faster.
In a run with such a curve near the commencement, therefore, and which is afterwards fairly straight, a higher mean of speed may actually result, as for the greater part of the run there is less wire in the water than would be the case in a straight run.  On the other hand, if considerable steering is continued during the run, a low speed may be expected.
Again, if the curve is very close in, the wire may follow up close, leaving little or no bight, there is little wire in the water, and a high speed may result even while on the curve.
Bights in the wire caused by tide may affect the speed in a similar manner.
The conditions which directly affect the speed, no doubt may also affect the slip of the propeller, and, therefore, the accuracy of the formulae; but this effect is very slight compared with the direct effect on the speed of the torpedo, and for the purposes of approximate comparison required it may be neglected, and the result of the formulae taken as sufficiently accurate.
It may be necessary at any time to run a torpedo at a vessel or target of an entirely different speed from that used in practice, and this target may approach so as to offer shots of various ranges and in various directions, which may also necessitate straight running or considerable steering at the start, &C.
To judge the time of launch and direction to take in such cases, it is of the greatest assistance to have some idea of the mean torpedo speed that may be expected in the particular case of shot.
This the calculated speed gives with quite sufficient accuracy if the results of normal runs of similar length and class are compared and the varying conditions noted.

156.   When a number of results of similar runs under normal conditions have been obtained and compared, it would be advantageous to tabulate the average mean speeds for a few typical classes of shot at ranges of, say, 500, 1,000, 1,500, and 2,000 yards.
When using this information in practice, outside influences, such as tide on torpedo and target, must of course be taken into account.
Besides the above use, abnormal differences in speed may show something wrong with gear, errors in measurement, drum turns, &C.

157.   Whilst the torpedo is getting up her speed, say during the first 100 yards, the efficiency of the propeller is not as great as later on in the run.
Experiments at a station where the torpedo takes her depth at once have shown that for the first 100 yards 170 revolutions of the propeller are necessary, but for the remainder of the run 140 revolutions per 100 yards are required.
In calculating the range, therefore, it is desirable to deduct 30 from the total drum turns in addition to those lost before the torpedo reaches the water.

That is all of it from this folder :)

Offline kyn

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Re: Brennan Torpedo
« Reply #98 on: July 10, 2014, 16:55:19 »
3 1/2 pages left!  I will be glad to finish it, as interesting as it is it does get a little tedious after a while :)

I do have one on the Fish torpedo too but think I will post a few pages rather than transcribing it all as it isn't much different to what is already in this thread.


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Re: Brennan Torpedo
« Reply #97 on: July 10, 2014, 16:24:30 »
This is a really interesting document, and reminds one how difficult it is to detail the exact instructions to be followed (reminds me of designing Artificial Intelligence).

Is there much more to do on the torpedo, kyn? It's been a massive undertaking - well worth it though.

Offline kyn

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Re: Brennan Torpedo
« Reply #96 on: July 09, 2014, 16:34:15 »

Offline kyn

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Re: Brennan Torpedo
« Reply #95 on: July 09, 2014, 13:54:26 »
V. – Records.


145.   Stress diagrams should always be taken.  The value of these diagrams can hardly be overestimated.  They assist in elucidating almost every abnormal occurrence which arises in practice, and in many cases it is only through the diagrams that the causes can be traced.  Even when some occurrence has taken place, of which there is no indication on the diagram, the absence of such indications often eliminates the possibility of causes which otherwise might have appeared likely.
It is not possible to enter into the interpretation of the diagrams.  This can only be learnt by experience and practice; Torpedo Officers should, therefore, always carefully examine them, tracing the sequence of events of the run on the diagram, even when there is no special point to elucidate.  By this means only can they become acquainted with all the indications, and get full value from the diagrams.
By this means also irregularities are sometimes found which are not otherwise noticeable, but which might become serious.
Diagrams should always be examined immediately after the run, while events are fresh in the memory, even though the more thorough investigation may have to be postponed.
In examination diagrams one should be superimposed on the other against the light, and the two compared.
Diagrams must be kept as clean and distinct as possible.  The stress, steering and clock pencils should be attended to and well pointed; they should not be too hard, and should be set with sufficient pressure to mark slightly heavily, as otherwise it is difficult to see through the superimposed paper.
In talking data from the diagram, no pencil mark should be made touching the actual stress curve, as it is found that this often renders it difficult to determine the precise original line on subsequent examination.  This does not refer to a sharp horizontal line at 900 or 1,000 lb. stress, which can be used if desired.
The rubber solution should be removed before the diagrams are put away.
Diagrams must never be inked in or pencilled over unless absolutely essential owing to bad marking.  It should not be necessary.
Diagrams will be headed with the name of the installation, and the following information will be given:-
Consecutive number of run, date, number of torpedo, whether right or left wire, and the readings of deducted drum turns and seconds used in the speed calculation for the run.

146.   Causes of Variation and Unreliability. – The circumference of the two recorder barrels may be found at some installations to vary slightly.  The effect of this is of course to make one diagram slightly longer than the other.  This is not sufficient to be material, but should be known exactly, so as to be borne in mind when examining the diagrams.
The chief points of importance to be looked to, which may cause variation and make the diagrams unreliable, are –
Variation in length between the diagrams (other than the possible permanent variation mentioned above).  This is usually due to the barrel not being securely clamped, but may be an indication that the screw fixing the dynamometer pulley to its spindle is loose or sheared.
Sticking of Dynamometer.  This is fully considered under ”Dynamometer,” Part II.  It renders the diagram quite unreliable for careful comparison.  It may be seen at once on the diagram by the absence, in places, of the usual slight vibration and undulations, and in worse cases, by the cutting off of rises or falls of stress, until finally, straight lines of considerable length are drawn.
It must also be seen that the paper is tight on the barrel, that the pencils cannot “wobble,” that the datum line is accurately drawn, and that the clock pencil is truly lined with the stress pencil.  The clock will be occasionally checked and regulated, and the connections looked to.

147.   Scales required. – Three scales are required for use with the diagram.
(1.)   A scale of stress.
(2.)   A scale of drum turns would in.
(3.)   A scale of steering.

(1.)   The scale of stress must be made at the station, and instructions for doing this are given below(see Dynamometer Scales).
(2.)   A scale of drum turns is supplied from the Brennan Torpedo Factory.  As the recorder barrel is revolved by the wire passing over the dynamometer pulley, and as all gear is made as accurately accurate for all ordinary purposes.  For extremely accurate experiments a special scale must be made by passing a known length of wire over the dynamometer pulley.  A;; data for making this scale, size of pulleys, gearing, length of wire in each later, &C., will be found in Part II.
(3.)   The scale of steering should be made locally by turning the steering wheel to various points in succession and marking the movement of the steering pencil on the barrel.
Copies of stress and steering scales should be forwarded with annual reports.

Dynamometer Scales.

148.   The following method of constructing dynamometer scales should be employed at all torpedo installations, except at the old installation at Sheerness.
In considering the best method for general use, facility of construction, together with accuracy, have been combined as far as possible.
It is found that the dynamometer spring occasionally vary slightly from one another.  A separate scale is, therefore, necessary for each wire.
The following method for constructing the scale, which is for one set of springs, should therefore be carried out separately for each set.
It may be well to point out that the law as to the extension of helical springs, i.e., that the extension of a helical spring is directly proportional to the force extending it, may be taken as always true within the limits of the spring.

Offline kyn

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Re: Brennan Torpedo
« Reply #94 on: July 08, 2014, 17:59:54 »

Offline kyn

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Re: Brennan Torpedo
« Reply #93 on: July 07, 2014, 18:41:45 »

138.   Storage and Treatment. – New rubbers will be stored in covered tanks of clean, fresh water, which should be changed occasionally.  Rubbers in use will be similarly kept in a separate receptacle.  Rubbers must be kept absolutely free from oil or grease, which injuriously affects the material.  Moreover, greasiness of the rubber is dangerous, and has caused them to spring out.
When the rubbers are taken from the fresh water receptacle, prior to use, they will, therefore, be washed in a solution of soda, and only inserted when quite dry and clean.
Rubber deteriorates rather quickly, especially in some climates.  Any rubber which show signs, on examination, of cracking, loss of the usual properties of good rubber, or perishing in any way, must be discarded.


139.   The following are the lubricants in use and their purposes.
Olive Oil. – For rubbing down the shells or torpedoes after running.  It is not very suitable as a lubricant for any of the torpedo gear, as it generally contains impurities which render it rather liable to dry and gum up.  It also often contains rather a large percentage of free acid.
Oil, Special for D.M.’s. – For depth mechanism, steering mechanism (torpedo), and steering box (Engine Room).  This oil was introduced on account of its comparative freedom from the above-mentioned defects of olive oil.
Vaseline. – (1.)   For protective purposes.
It should be freely used wherever protection from rust in required, when there is no objection to a greasy surface.  This applies to nearly all the steel parts of the internal mechanism of the torpedo, to spare parts, and probably many installation articles.
(2.)   As a lubricant.
It is an extremely good lubricant, and should be used for all ball and roller bearings, and all the parts that are regularly lubricated by smearing, as well as for bearings, which do not get regular and frequent lubrication, e.g., shaft bearings, thrust rings, ring ejecting gear, chain pulley bearings, rudder bearings, rudder axles, &C.  It should be warmed for use in the syringes.
Caster Oil. – For dressing, preserving, and lubricating diaphragm leathers, all cup leathers, leather washers, &C.
It is a very food dressing, and also an excellent lubricant.
Paraffin is excellent for cleansing bearings, removing rust , &C.

Wire, Storage, and Treatment.

All wires are examined and tested at the Brennan Torpedo Factory and are issued ready for use, packed in quicklime, and protected by wrappings of paper.  Each hank is issued with a metal label attached to it, stamped with the number of the hank, the nominal diameter and net weight of the hank.  Further particulars are given on the invoice of the wire.
New hanks will be kept in quicklime until required for coiling.
Wire must be very carefully handled; the hanks should be lifted with care, and never dragged.  The binding wire must not be too tightly screwed up.
All wires must be most carefully protected from damp.

141.   Service Wires. – The wires which five the best results under test are selected for issue as service wires.  Special precautions must be taken with these wires, and they will be dealt with as soon as possible after receipt at an installation.
Service wires should be coiled in a dry atmosphere.
The wire will be passed through cotton waste held near the drum, and just sufficiently oiled to be greasy and no more.
Care will be taken that the wire does not come into contact with the hand, or anything damp, and, especially in cold weather, breathing on the wires should be avoided.
Twine will not be used for fastening.  Soft-tinned wire, about .03-inch diameter, is the best material to use.  It is rather difficult to ensure locally tinned wire being free from acid, but as sold it appears to be so.  The binding wire should be dry and oiled.
As soon as possible after coiling, the wires will be placed in the steel boxes provided for the purpose, in each of which a box or bag containing 2 or 3 lb. of fresh, dry quicklime will be placed om such a manner as to prevent, as far as possible, the lime being spilt.
The boxes will then be closed as under:-

142.   Closing Air-tight Steel Boxes for Service Wires. – The cover joint will be made with tarred 3-thread hemp spun yarn.
The spun yarn for each box should be in one continuous length, for convenience in readily breaking the joint, and will be thoroughly soaked in a melting (not boiling) mixture of 5 parts white lead and 1 part Russian tallow (used to prevent the packing setting hard).  It should be well pressed in, and lightly caulked, layer by layer, until the space between the cover and the box is full.
Every means available must be taken to ensure that the boxes are thoroughly dry, and that the operation of closing is carried out in a dry atmosphere in order to avoid, as far as possible, the slightest condensation of moisture inside them.

143.   Use of Service Wires. – Three pairs of service wires should be converted to practice and expended every year, so that the wires may be gradually replaced.
The oldest wires will be taken for use.
It is advisable to first use these wires on any special occasions which may arise in the curse of the year, when it is particularly desirable to minimise chances of failure.
In order that the installation may not be without its compliment of service wires, demands to replace those it is intended to expend will be sent in annually.  On receipt of the new wires they will as soon as possible be stored in the air-tight boxes, those removed being retained for use as above.

Mast stays.

144.   Mast stays are issued packed in lime in metal cylinders, 6 pairs in each cylinder.  The cylinders should only be opened as required.
With fair use and handling these stays would last for a considerable time, but it is advisable to discard them after they have been used for 10 or 12 runs.
They should be carefully examined before use, and any which have become damaged, rusted, or show signs of drawing or deterioration at the soldered loops should be discarded.
Two or three pairs only should be in use at one time for practice.  If stays are fitted to service masts they should be carefully looked after and oiled.

Offline kyn

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Re: Brennan Torpedo
« Reply #92 on: July 05, 2014, 16:54:38 »
Faults in Flexible Cables.

132.   Should a fault be detected in a flexible cable it will be necessary to remove and remake one of the special junctions.

133.   There are three sorts of these-
(1.)   The small spigot to fix to the sending instrument.
(2.)   The large spigot.
(3.)   The socket.

134.   Great care must be taken in remaking any of these joints to connect the cores to their correct contact pieces.
The cores should be connected to the contacts on the large spigot, as shown on Figure 1, Plate III.  From this the correct connection to the sockets and to the small spigot can be followed, it being remembered that the latter has to fit into the socket on the sending instrument, the contacts of which are numbered.

135.   If the connections at the small spigot, Figure 2, Plate III, are defective, it can be dismantled by slightly warming the spigot to lessen the chance of the “pudding” sticking to the ebonite, then gripping the end of the spigot and unscrewing the ebonite shoulder, the end of the spigot then comes off exposing the ends of the cable soldered to the contacts on the ivory block.  This operation has to be carried out with the greatest care as the ivory block easily breaks.  It will be seen from figure 2, Plate III., that each core is led up through its hole in the ivory block, bent over into its groove and soldered in.  These can be removed by unsoldering with the bolt, and then if the pudding is removed the ivory block can be freed.
In the remaking, the pudding should be formed of paraffined string, and before screwing together it should be smeared with Vaseline.  In soldering no acid should be used.
The above is a troublesome operation, and unless very urgently required it would be better to demand another short length complete from the torpedo factory.

136.   The details of the large spigot are simpler (Figure 3, Plate III.).
To dismantle, remove the screws holding the ebonite block, warm the spigot so that the hand can barely hold it, then push the pudding and ebonite block out.  The connections for the cable are obvious.  The pudding should be remade with string and bicycle cement.

137.   The dismantling of the socket should be carried out in a similar way to that of the spigot, but before doing this it is well to remove the ebonite cap holding in the spring contacts to discover whether the fault is in these.

Offline kyn

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Re: Brennan Torpedo
« Reply #91 on: July 03, 2014, 17:00:22 »
Sending Instrument, Quick Return, Binocular.

131.   (a.)   The instrument consists, generally, of one main casting, carrying all the telegraph mechanism and connections, and a pair of binocular glasses attached to, but practically independent of, the main casting.
To separate the glasses from the casting it is only necessary to push the dark glasses well aside, and to remove the hexagon nuts on the front of the instrument with the clamping key provided; the two portions then come apart.
The instrument should, however, be dismantled as little as possible.  The glasses should be considered solely as part of the instrument, and their removal for use apart should be strictly forbidden.

(b.)   Main casting. – The main casting consists of a stem with a box on the top, which box has a cover easily removable after slackening the two brass screws at the sides.
Under the stem are the spring contacts, which make the connections with the cable leads.
These contacts are protected by a cap, which can be unscrewed after the removing the small screw at the back.  On the removal of the cap the ebonite block, which carries the contacts, is exposed.
The block is secured normally by the cap, but, on the removal of this, by the leads only; the block should, therefore, not be further interfered with, unless the leads are being renewed, as damage to the latter is likely to result.  A pin determines the correct position of the block, and so of the contacts.
The fine leads from the contacts run up through two holes in the stem to the box above.  In the box is an ebonite base, through two corresponding holes in which the leads pass to their respective terminals.
The ebonite base, which was attached by two screws to the bottom of the box, carries all the terminals (except those of the telephone receiver), and the mechanism of the pushes, the electrical connections here being by permanent metal strips.
The mechanism is simple and requires no explanation.  The contacts are made by phosphor-bronze springs bearing platinized strips, against platinized stops, and the movement of the pushes and springs is such as to ensure ample time and a slightly rubbing movement for each contact, if the pushes, as they always should be, are pressed home.
The telephone receiver is attached to the front of the casting, the attachments passing through the front of the box and forming the terminals inside.  These and the receiver should, therefore, not be unnecessarily removed, as to do so it is necessary to dismantle the receiver.
It will be seen from the foregoing that there are no moving leads, as in previous instruments of this type.
As regards watertightness, the cover of the box is overhung, leathers cover the pushes (spare ones will be found in the box), and a parafinned washer between the receiver and the front of the casting prevents the percolation of water here.  The instrument is thus considerably protected, but, nevertheless, should not, or course, be unnecessarily exposed to wet, and after any unavoidable severe exposure of the kind, the cover should be removed and the interior of the box examined.
Should the ebonite base ever be removed, the protection of the hidden portions of the leads should be ensured by stopping the holes with paraffin wax, and making a joint between the ebonite base and the bottom of the box, round the holes, with indiarubber solution, a thin cork washer, or in some similar manner.
Should the ebonite base ever be removed, the protection of the hidden portions of the leads should be ensured by stopped the holes with paraffin wax, and making a joint between the ebonite base and the bottom of the box, round the holes, with indiarubber solution, a thin cork washer, or in some similar manner.
Three projections on the front of the casting form feet for conveniently standing the instrument while keeping all material parts clear of the ground.

(c.)   Glasses. – The glasses are Zeiss marine pattern night binoculars.  This pattern was selected after considerable trial as combing in a high degree the chief requisites for torpedo work, viz.: - good light, definition, stereoscopic effect, and field, with sufficient magnifying power.

(d.)   Adjustment of Glasses. – The moveable eye pieces allow of adjustment for focus for each eye separately, and a scale on the eye piece enables this adjustment to be noted for any individual.
With this type of glass the correct adjustment for pupillary distance (the distance between eyes) is very important.  It will be noticed that the increase of light and definition when this adjustment is correct is most marked.
The attachment has, therefore, been so designed as to allow easy adjustment ad full latitude and full latitude in this respect.  The hexagon nuts which form the attachment have been alluded to earlier.  When these are slightly slackened with the clamping key, the glasses are free to move, and the adjustment can be made.  The correct setting for any individual can be noted on the celluloid scale.
When the glasses are being used by several persons the nuts can be just so adjusted as to give a convenient stiffness of motion.  Normally, however, the glasses should be as far as possible kept clamped to the setting of the usual observer, as the metal used (for the sake of lightness) is not a very good wearing metal.  The instrument will fit into the box with the glasses at any setting.
The sliding surfaces should be kept very lightly vaselined.
Dark Glasses are provided for use when running in the sun.  These normally lie over the above-mentioned nuts, and only need to be pushed into position over the object-glasses when required.  Spare discs are provided in case of breakage.  These will probably fit the rings sufficiently well, but they can be cemented in if necessary.

(e.)   Dismantling the glasses. – The glasses are delicate, and should only be interfered with if absolutely necessary.
The back and front cover plates should never be removed, as these fix the prisms, the absolutely correct adjustment of which is essential and very delicate.
The same applies even more to the bracket attachments to each half which carry the centre pin, as on their precise adjustment depends the parallelism of the glasses.
Should it become necessary to clean the glasses, extreme care should be exercised.  It is difficult not to actually introduce dust in the operation, and opening up the glasses at all allows, of course, the entrance of any particles in the air.
The object glasses can be unscrewed after removing the extremely fine screw which will be found in the rim of the front cover plate.  Certain faces of the prisms are then exposed, and a speck of dust may be removed with a camel hair brush.  If any further cleaning is required washleather, or silk on the end of a piece of wood, is perhaps best; but whatever the brush or material used, it must be absolutely dry, clean and free from dust, hairs, or fluff, or much trouble will be experienced.
To remove the eye-pieces the adjustable covers must first be taken off.  These can be unscrewed after removing the small screw which will be found thereon.  The whole eye-piece can then be unscrewed from the back cover plate.
Other faces of the prisms can then be got at as above.
The eye pieces should not be further dismantled; they are believed to be absolutely dust and damp proof, so that the lenses are not likely ever to require cleaning on the inside.

(f.)   Cables and Connections. – The system of flexible cables and connections is as follows:-

There are two lengths of cable, a short length (approximately 7 feet) and a long length (about 50 yards).
Each short length has one ordinary spigot, and one special spigot for connection to the instrument; each long length has one ordinary spigot and one socket.
The short length, then, though a necessary adjunct of the instrument, is separate from it, and can be changed when necessary, while any number of intermediate long lengths can be connected together on the hose pipe principle.
Thus the instrument with the short length attached, can be connected direct on to a junction-box, or on to the end of one or more long lengths, as desired.

(g.)   Use of Instrument. – The instrument should be kept as far as possible in the box when being carried about, but the strap will be found convenient when it is actually in use.
Various points in connection with the use of the sending instrument are noted under the heading “Practice.”
The note on the cover of the box is merely a reminder, and requires some amplification for those not thoroughly acquainted with the instrument.
In this respect the effect of manipulation of the sending instrument depends, of course, on the mechanism of the dials.
Assuming the dial pointer to be at zero, no contacts having been made either way, the maximum number of movements of the pointer in one direction, R or L, is 11.  It is immaterial whether these 11 movements in the opposite direction, so long as 11 in all have been made in one direction.
For instance, suppose contacts are made in the following sequence: 5 R, 5 L, 4 R, 2 R.  The pointer will then finally be at 4 R, but since in all 11 Right contacts have been made, further pressing of the Right button will have no effect.
For any further effect to be obtained by pressing the Right button it is necessary first to “wipe out,” so to speak, all that has gone before, by the “quick return”; i.e., to bring the dial pointer to zero by pressing both buttons simultaneously.
It follows that though the practice of “taking off” a certain number of steps in one direction by making contacts in the opposite direction is often useful – especially where small effects are concerned – it should be done with discrimination, or is liable to lead to error.
In the case of considerable movements, or where there is liability to forget precisely what has gone before (as when an order has been on for some time, or several small movements have been made and “taken off”), it is always safer to “zero” first.  The term “zero” is always used in the sense of bringing the dial pointer central by the “quick return”.
In the case of engine dials, especially, “zero” should, as a general rule, be given before an order when the previous order has been on some time, so this not only prevents error, but helps, by the additional strokes on the bell, to call the attention of the engine room.
The time lost by “zeroing” in this way is practically imperceptible, as neither the engine driver not the man at the steering wheel can follow the orders sufficiently quickly for it to be material.
Though the above statement as regards the maximum of 11 contacts is true enough for practical purposes, it is not strictly so, and it is as well to point out where this is the case.
If 11 contacts in all have been made in one direction, the first contact then made in the opposite direction brings the pointer back two steps, one of which can then be put on again by making contact in the original direction.
For instance, suppose 11 R has been given; 1 L will then bring the pointer back two steps, i.e., to the ninth division, and one of these can be put on again by making one or more Right contacts, thus bringing the pointer to the 10th division.  The pointer can thus be brought back from extreme Right to within one of zero by making L and R contacts alternately.
This can be seen by trial with the instrument connected direct on to the dials.  It is not a condition which is of the slightest importance in actual use, but it is as well it should be known, as it has led to the impression that the dial is defective.

Offline kyn

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Re: Brennan Torpedo
« Reply #90 on: July 01, 2014, 17:33:12 »
Examination and Cleaning of Dials.

129.   The dial will be examined-

(1.)   Annually.
(2.)   When it fails under test.

If the examination is for a failure, it should be seen that the pointer is firmly fixed and the failure not due to its slipping.
It should be seen that the dial case in on a flat bed.
This will normally be the case, but failure has been known to occur owing to the steering dial being raised on scotches, and screwed down in that position in such a way as to produce slight distortion and consequent binding of the mechanism.
The mechanism will then be examined.
The pointer and dial face being removed, the centre body of the mechanism can be lifted out, clear of the magnets, &C., after turning the three half-headed holding-down screws to the required angle.
The mechanism so removed will on no account be further taken to pieces, or the adjustments or springs interfered with in any way (except the bent wire spring, as described later).
The mechanism will be examined, and any dirt or dust which may have found its way in, and which is easily removeable with a brush or otherwise, should be removed.
When it appears necessary, on examination, and in any case at the annual examination, the mechanism will be very lightly and carefully oiled with a few drops of instrument oil; a fine-pointed piece of wool, which only holds a small drop of oil on the end, is the most convenient means.
On no account whatever will any oil, except clean, pure, instrument oil (not D.M. oil) be used for this purpose.
The adjustment of this mechanism requires very great experience.  It must, therefore, be very carefully handled, and, if there is any defect which necessitates taking to pieces or readjustment, it is advisable to return the dial for repair.
Care must be taken, when removing and replacing the mechanism, not to injure the fine wire leads in the dial case.
When refixing the pointer the special small spanner, issued for the purpose, will be used.
The pointer cannot be easily fixed sufficiently firmly with the fingers, but is very liable to damage if too great force is used.
The springs are easily removable without disturbing the mechanism, but must be carefully handled.  A few spare springs are being issued in case any are ever broken.
In all tests of dials it must be seen that the bell on the engine dial rings with a clear full stroke.

130.   The results of the periodical tests laid down, viz:-

Half-yearly test of number of cells required (giving approximate length of cable and lead);
Annual test of dials.

will be embodied in annual reports.
When testing the engine order dial for the “minimum” number of cells necessary, it may be found that the dial still works with certainty, with a number of cells insufficient to ring the bell satisfactory, i.e., that the bell fails before the dial, or the opposite may be found.
The missing of an occasional stroke by the bell when the dial is being tested rapidly backwards and forwards is immaterial, and will not be considered failure of the bell.  Failure of the bell is when it fails to ring, of to ring loud and clear on a single movement (or zero on the “quick return”) of the dial, or through a series of contacts when the dial is being worked at ordinarily fast pace.
The most desirable condition is that the dial and bell should fail practically simultaneously, or the dial slightly before the bell.
It should, however, be borne in mind that it is far more essential for the bell to ring normally with a full, loud stroke than for the above condition to be complied with.  Moreover, the instruments vary somewhat, and it does not follow that this condition can be attained.
The adjustment of the bell is made by turning the milled-headed screw under the box (after removing the gong).  Turning to the right shortens the stroke, and therefore, diminishes the number of cells required, and vice versa.
With reference to the above dial tests, it must be remembered that the less the dials are interfered with, except for annual examination or on failure, the better.
It is advisable that such examination should never be made except by an Officer.


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