APPENDIX M.

TANNER SOUNDING MACHINE.

The machine, Plate C, is mounted on the rail in readiness for sounding. The spindle, a, which ships in the rail, is of wrought iron, screwed firmly into the base of the brass frame b, that carries the reel. The frame above mentioned is cast in one piece, is bored to receive the shaft, and has appropriate lugs for the paul, register, clamp f, spindle, and arm at i. The reel, cc, is of cast brass and will hold 2000 fathoms of sounding wire, one fathom to a turn on the first layer, increasing as the score is filled. The friction groove common to all sounding reels is on the right side.

The cranks, d, e, by which the reel is turned, have conical friction surfaces, which are brought into action by turning the right crank, e, half a turn ahead, crank d remaining clamped, or held firmly in the hand. The reverse motion releases the reel and it turns freely without moving the cranks.

On the left of the frame, between it and the crank is a worm wheel which operates the register. The ratchet and paul are on the right, between the frame and crank. The arm g, supporting the guide pulley h, is of flat bar iron, its lower end riveted to the frame between the lugs, i. The later machines have a hinge at this point composed of a single bolt and pin; the latter being withdrawn, the arm lowers, bringing the guide pulley inside of the frame, when the reel is unshipped.

The small metal block, j, projecting from the arm, is part of a tackle for suspending the reel when mounting and dismounting. The guide pulley, h, is of brass, with a deep groove for the wire; it works between guides which terminate in a spindle enclosed in a brass cylinder, p. The pulley is suspended by a coiled spring surrounding the spindle above mentioned, which allows it a vertical motion of about three inches. A brass guard surrounds the upper portion of the pulley to prevent the wire from flying off if suddenly slacked." A small arm, k, projects from the upper end of the spindle and works through a slot in the cylinder p. The standing part of the friction line is secured to the eye n, carried around the reel in the friction groove to m, where a small line, 1, is made fast to it on the bight, one end being made fast to the arm g, and the other to the arm k, the slack of the line being taken in before the weight of the lead is taken on the sounding line. In this position considerable force will be required to move the reel; but the lead being suspended, the spring is compressed and the tension on the friction line relieved, allowing the reel to revolve freely.

A Negretti and Zambra deep-sea thermometer in the wooden case furnished by the makers is shown at q. The same thermometer in Tanner's metal case is shown at r; the metal messenger which is sent down on the wire to release the slip hooks and reverse the thermometer is suspended at s. The comparative sizes of the ordinary deep-sea lead line, the hand line, and sounding wire are shown at t, u, v.

The machine turns freely, the guide pulley taking the direction of the wire if, from any cause, it trends out of the perpendicular. A set screw is provided in the rail bearing for clamping the machine to steady it while heaving in.

The reel is usually kept in a tank of oil when not in use, to preserve the wire. By an ingenious arrangement, for which we are indebted to Mr. Tippet, draughtsman at the Ordnance Department, Navy Yard, Washington, D. C., the reel is unshipped by simply unscrewing the nut o, shown on the face of crank, d, and withdrawing the shaft to the right, leaving the ratchet, worm wheel, and crank ₫ in position.

The total weight of the machine is 128 lbs.

The wire used is purchased from the Washburn and Moen Manufacturing Company, Worcester, Mass., and is called by them "No. 11, Music"; it weighs