APPENDIX.

1. Specimens of small-arms ammunition.

The caliber 0.50 of these specimens of small-arms ammunition is the standard service cartridge of the United States Navy, manufactured at the "United States Cartridge Company's" factory at Lowell, Mass. This cartridge is of the type known as solid-head, reloading and outside primed cartridge. It is made from an alloy of copper and zinc. The mixture is intended to give the greatest tenacity with the necessary ductility for the manufacture. The metal is first rolled into sheets 80 of an inch in thickness; from these sheets a disk is punched which takes a cup form by being forced through a proper-shaped die; from this cup the shell is drawn to its proper length, having a surplus of metal at its closed end. The next process is to form the head, which is done by flowing the metal into the proper form, leaving it ready to receive its primer, powder-charge, and bullet.

The primer consists of two cups, one within another, with a fulminating compound between them; the inner cup has two perforations. This primer is inserted within the pocket made for it in the head of the shell, and is exploded by a blow, and the fire communicated to the powder through the perforations. The metal shell weighs 165 grains, the powder charge 70 grains, and the bullet 450 grains. The lubricator is barberry wax placed in the grooves of the bullet, and the powder is that manufactured by the Oriental Powder Company under the direction of the United States Navy Department.

The special features of this cartridge are―

1. It is impossible to burst the head by any charge of powder; and,

2. Its great safety in transportation.

2. Chronometers at the United States Naval Observatory.

The Naval Observatory at Washington is the depot for all chronometers belonging to the United States Navy. They are issued from this institution to all ships of the Navy that go into commission, and they are received there from vessels after the completion of a cruise. The chronometers on hand are kept together in one room in the east wing of the building, which room contains also the standard mean-time clock of the Observatory. The chronometers are arranged in wooden cases, which fill the center and the sides of the chronometer room. These cases are capable of containing two hundred and two chronometers when all filled. The temperature of the apartment is always about that of the outside air. No artificial means are employed to keep the room at an even temperature, but the variation of temperature is observed each twenty-four hours by means of a self-registering maximum and minimum thermometer. Chronometers are purchased for the Navy, when required, by the Bureau of Navigation, the preference being given to those of American manufacture. Before the final purchase of an instrument, it is subjected to a trial of six months at the Observatory. All chronometers on hand are wound and compared with the standard mean-time clock, daily, at noon. The error and rate of the clock are determined by observations with the transit circle at intervals of five or six days, or oftener if the weather permits.

On every tenth day the actual error of each chronometer on Greenwich mean time is computed, together with its rate during the ten days preceding, and these results, 4 CEN, PT 2.

49

with the mean maximum, mean minimum, and average temperature during the ten days are entered in the rate-book, in which one page is assigned to each chronometer on hand. Thus, a glance at the columns of the rate-book will show the actual performance of any instrument during the time it has been at the Observatory.

The firm of Messrs. T. S. & J. D. Negus, of New York, are regularly employed by the Bureau of Navigation for the cleaning and repair of chronometers. All instruments which, in the judgment of the Superintendent, may need cleaning or repairs are sent to them, and the prices of their work are fixed by contract. No chronometer is allowed to run more than four years without cleaning; and after an instrument has been cleaned or repaired it is subjected to the same trial as those offered for purchase. If it is rejected on trial, it is sent to Messrs. Negus for readjustment. Thirty years is considered the lifetime of a chronometer. Those that are worn out in the service, or are found to be otherwise unfit for issue, are condemned by an order from the Bureau or Navigation, on a representation of the facts of the case from the Superintendent. These condemned instruments are carefully packed and stored at the Observatory. They are sometimes issued, by order of the Bureau. to shore stations or receiving-ships as local timekeepers, but never, under any circumstances, to sea-going ships.

Chronometers on hand for issue, that is, those which have passed trial subsequent to purchase or repairs, are compared with the standard clock, as above noticed, and the record of their errors and rates kept in the rate-book.

Chronometers on trial are also compared every day with the standard clock. At the end of six months the trial number of each instrument is computed by the following rule:

Find the mean daily rate and extreme daily variation for each month in the period of trial; add twice the difference between the greatest and the least of the monthly rates to the mean of the monthly variations.

If the trial number exceed eight seconds, the chronometer is rejected.

When a chronometer is received at the Observatory, it is placed under comparison from the day of its receipt, and its record in the rate-book opens on the first rate-day after its receipt.

Chronometers issued to vessels are accompanied by a paper showing their errors and rates at the time of leaving the Observatory, and the mean rate for every 10° of temperature from 40° to 80° Fahrenheit. These instruments are always sent to a distant station in charge of an officer or other competent person. If the journey is to be made by rail, the instruments are packed in a basket with.cotton.

In addition to the rate-book already mentioned, a history-book is also kept, in which each chronometer occupies a page, and in which are entered its date of purchase, price, and trial number, with a description of the instrument, and its subsequent history. For convenience of reference, the history-books and rate-books are indexed in a separate volume.

There are at present on the records of the office 812 chronometers. Of these, 12 are pocket-chronometers, 9 are adjusted to sidereal time, and 108 have been condemned and stored at the Observatory. Of this number some have been also lost at sea.

There are 60 mean-time chronometers, 4 sidereal chronometers, and 3 pocket chronometers on hand at the Observatory, ready for issue. Of the remainder, some are in actual use on board ship and at naval stations; some are retained at Mare Island, California, for the supply of ships of the Pacific fleet, and some are in the bands of Messrs. Negus, under repairs.

The greatest number ever held ready for issue at the Observatory during the last five years is 125.

The least number on hand at one time during the same period is 31.

The average number on hand per month during the same period is 83.

The telegraphic apparatus for transmitting the exact instant of noon to the Western Union Telegraph office, and for dropping the time-ball on the dome of the Observatory, is in the chronometer-room, and is used in connection with the standard mean-time clock.

3. Navy Compasses.

Three specimens, comprising Nos. 8826, 8827, and 8828 of the makers, are exhibited. These are used as standard and steering compasses in the United States Navy, to the exclusion of all others. The bowl-circles of these compasses are fitted to a uniform gauge. The two card-magnets are compound, being built up of thin laminæ, hardened and tempered throughout their length and magnetized to their utmost. The magnet piles are set edgewise to the plane of the card. The card-circle (or graduated annulus) is adjusted into position, before fixing upon the card, to coincidence between its line of zeros and the magnetic axis of the card.

The two card-magnets weigh 1760 grains : card is 3720 grains

=

240 grams.

=

114 grams; and the whole weight of the

The pressure on the pivot in the liquid medium is 60 grains at 60 Fahrenheit, or about 4 grams at 1510 Centigrade.

4. Hanging or cabin compasses.

Two specimens, including Nos. 8981 and 8982, are exhibited. The exterior of these compasses is nickelized for convenience in keeping, it haying been determined that no appreciable deviation arises from either fixed or changeable magnetism in this coating. The card of this compass is adjusted to a minimum upward pressure against the pivot; that is to say, to about 60 grains at a temperature of 60° Fahrenheit. 5. Azimuth circle.

Two specimens, comprising Nos. 39 and 40, are exhibited. These circles are interchangeable upon every navy compass.

6. Turret or monitor compass.

This compass, inside of its outer case, consists of a vertical spindle, with upper and lower bearings, carrying a magnet-float above and a reading-card below, the whole being so far buoyant as to have sensibly the same specific gravity as that of the liquid medium; while an interior gimbal-action, at the magnet-float, provides for all necessary inclinations of the latter in consequence of any rolling or pitching motions of the ship.

This compass is placed in the common vertical axis of the gun-turret and pilothouse above; and it is so fixed in the roof of the latter as to bring the reading-card just below or inside, and the magnet float about 7 feet above or outside of that roof. 7. Old compasses of the U. S. Nary.

A dozen specimens of these compasses have been selected from those in store at the Boston and New York navy-yards, comprising such as were in use from 1820 to 1870; and they are exhibited to illustrate the grave defects of the oldest, as well as to show the progress made towards the better ones last in use.

8. Compass-testing instrument.

This instrument was designed by the Superintendent of Compasses as a portable substitute for the fixed compass observatory near Boston; it being sometimes desirable to have the means of examining the compasses which have been turned into store from ships going out of commission at a navy-yard, before they are otherwise handled in returning them for repairs or refitting at Boston.

9. Magnetic collimator.

This instrument was devised by Mr. E. S. Ritchie, of Boston. It is intended to serve as a substitute for the collimator of the ordinary form; that is, with a suspended magnet. Experience has demonstrated its sufficient sensibility, as well as its practical convenience in use. Its magnetic axis is defined by comparisons with a suspended

collimator.

10. Adjustable binnacle for correcting the deviation of the compass.

This apparatus was designed by the Superintendent of Compasses to serve more es pecially as a steering binnacle for the new iron ships Alert, Huron, and Ranger,

of the U. S. Navy; but it is intended to serve equally well on board any ship whose magnetic forces, acting at a particular compass position, are of sufficient magnitude to make it expedient to effect their neutralization. The apparatus has polar, quadrantal, and vertical correctors. Each corrector is definitely adjustable to the required distance and direction with respect to the center of the compass card, and admits of being definitely registered in accordance with a prescribed form; while it also admits of being retouched, and again recorded, in the same definite manner, as found expedient from observations subsequent to those made at the port of outfit upon which the first adjustment was based.

11. Gravitation compass, designed by the Earl of Caithness.

This compass has the distinctive peculiarity of a heavy pendulum, which is attached to the bottom of the compass-bowl, and is claimed by its inventor to improve the stability of the bowl, this being hung in gimbals in the ordinary manner. The compass is suspended in a closed binnacle, which is provided with movable magnet-holders for the correction of the compass deviation.

12. Deep-sea sounding machine.

(Designed by Sir William Thomson, and modified by Captain G. E. Belknap, U. S. N.) This machine consists of the drum for the wire, with its supports, counter, and crank; the dynamometer or spring-balance wheel, with its support and dynamometer; and the endless rope with its pulley-wheel, pendant, weight-attachments, and stanchion.

The wire is reeled on the large groove of the drum, the different lengths between the splices having been previously measured; and in reeling it on the drum the number of revolutions between the splices must be noted. One bight of the endless rope is placed over the V-groove of the drum, and the part leading from the bottom of the drum is taken up over the dynamometer-wheel and once around it, and the other bigat of the rope is kept taut by being placed over the pulleywheel, to which a pendant is attached, which is rove through a block secured to a stanchion; to the end of the pendant weights are attached which keep the pendant and endless rope taut, by means of which the revolutions of the drum may be regulated as desired. The dynamometer-wheel and dynamometer are connected by a cord or check-line which is secured to a hole in the rim of the dynamometer-wheel, and the other end is attached to the eye in the end of the spring balance.

The specimen-apparatus is attached to the wire; it consists of Belknap's cylinders with the Brooke's detaching arm. The sinkers are bored shot, and are fitted with two lugs, to which lanyards are attached, which go over the detaching arm.

The counter registers the number of revolutions of the drum, from which the depth is computed.

On reaching bottom the sinker will detach, and the upper cylinder will fall over the lower one, which has already taken up the bottom specimen.

The moment of the cylinder's touching bottom will be shown by the stopping of the revolutions of the drum and by the action of the spring-balance.

The greatest depth reached by means of this machine was 4,655 fathoms, 27,930 feet. 13. Sir William Thomson's detaching apparatus for deep-sea soundings by piano-forte wire. The tube to bring up specimens of bottom has attached to it a bolt, which is held in position by a light spring. With the bolt in this position when the bottom is reached, the tube is pressed by the weight of the sinker until it penetrates so deep that the sinker rests on the bottom, or till the whole weight is borne on the tube, as is the case when the bottom is stiff clay. Independently of this action, the detaching apparatus acts when the weight is nearly all borne on the bottom; a spring double-claw opens, and leaves the sinker free, except so far as the tube and bolt influence it. Then, when hauling up commences, a slight cord attached to the bolt releases it and brings up the tube, leaving the sinker on the bottom.

Professor Fleeming Jenkin's dynamometric brake, as applied to deep-sea sounding, is shown in connection with the preceding.

Whatever weight is borne on the free end of the brake-cord, the whole tangential resistance applied to the running wheel is equal to this weight within a very small percentage of its amount.

In the two parts of the brake-cord where it leaves tangentially the running wheel, let T and T' be the tensions so that T-T' is the whole tangential resistance actually applied to the wheel. Let rand be the radii of the greater and smaller brakedrums, and let W be the weight borne on the free part of the brake-cord hanging down tangentially from the larger brake-drum. For the equilibrium of the double brakedrum we have: Wr=Tr-T'r'; hence,

14. Belknap's specimen cylinder No. 1.

Is designed for bringing up bottom water as well as ooze or mud.

15. Belknap's specimen cylinder No. 2.

Is designed for hard sandy bottom, but will also work well where soft bottom is found.

16. Belknap's specimen cylinder No. 3.

Is designed for use where ooze, mud, or clay may be found.

17. Belknap's specimen cylinder No. 4.

Is designed for use in sandy or gravelly bottom.

18. Collins's detaching and specimen apparatus.

The object of this apparatus is to make use of the ordinary shot as sinkers, without perforation or other preparation.

In preparing this apparatus for use, withdraw the specimen cup and attachments from the cylinder as far as possible and insert a wooden chock to prevent re-entering; place the sinker on the top of the cylinder and the crown on the top of the sinker. Then compress the spring and place the rings of the straps over two opposite lugs of the detaching ring. Then release the spring, withdraw the chock, and the apparatus is ready for letting go.

On reaching bottom, the resistance causes the specimen box to slide up, carrying the detaching ring with the cylinder, thus releasing the straps and permitting the sinker to fall off. The specimen of the bottom enters through the aperture closed by the conical valve (as in the Belknap cylinder No. 2), as well as over the top of the box in case of soft bottom.

19. Bunting testing apparatus. (Designed by Commander R. W. Meade, U. S. Navy.) Directions for use. The test pieces of bunting being properly cut, are placed in the clamps in the following manner: One-half of each clamp is placed in position by using the distance-board, the bunting is then laid so that the outer threads are the same distance from the screw holes. The upper parts of the clamps are then put on and the screws sent evenly home. The distance-board receives the large clamp at its open end, hook part of the clamp down and out.

To connect the lever with the clamps, enter the small clamp in the grooves prepared for it, and raise the long arm of the lever until the upper clamp can be hooked on to the short arm; let down the lever carefully to adjust the small clamp so that the bunting may have a direct strain.

Turn carefully the crank, and note from the forward side of the slide which carries the weight the marks at which the bunting breaks.

The figures represent pounds. Avoid hastening the speed of the weight when nearing the breaking point.