Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

“ The diamond boring tool was a steel annular ring 2|in. in diameter and |in. thick, studded with diamonds overlapping one another. This annular ring, or crown, was screwed on to the bottom of the boring rod, which, in. suitable lengths, was carried inside an iron guide-tube, extending down to the bottom of the river bed. The rod was connected at the top to a drill bar suspended from an iron diagonal framework on the barge. Rotary motion was given to the drills by means of phosphor-bronze bevel wheels, working in a frame and driven fiorn the main shaft on deck by an ingenious arrangement of ropes and loose pulleys, which allowed for any lateral or vertical movement of the drill through rough weather, the rise and fall of the tide, and the ranging of the barge through the suction of passing steamers. The drill-bar was driven at the rate of 400 revolutions per minute, and during the whole time that the boring was proceeding, water, at a pressure of 4olbs. per square inch, was forced down through the hollow boring rod to wash out the detritus and keep the face of the diamond crown cool. The piessure of the drill was applied by means of counter- balance weights, varied according to the hardness of the rock being bored. In the hard blue whinstone the boring of the holes of 2|in. diameter proceeded at the rate of 2ft. per hour, and 5ft. per hour in softer stone. When the necessary depth of hole was bored the drill rods were withdrawn, and the dynamite charges were fitted with detonators and fixed in the holes. Attached to each charge were electric cables, which were led up to the surface of the water. AH the charges were then connected, and the shot-hole wires were attached to a main cable, which was carried to the positive and. negative poles of an electric exploder. The barge was then withdrawn about 60ft. from the place of the explosion, and the row of eight holes was fired simultaneously, resulting in the displacement of something like 100 tons of rock; the only disturbance was a slight upheaval of water. The greatest amount lifted by the dredger in one day was 280 tons. A diving bell afterwards went over the ground, and re- moved any large stones that had been left by the dredger. “ More readily to convey an idea of the amount of labour involved in the removal of rock, it may be stated that something like 16,000 holes were bored, equal to about 90,000 lineal feet. About 110,000 tons of whinstone and boulder clay were dredged. About 76,0001b. of Dynamite and other explosives were used without loss of life or damage to limb, and were exploded by means of about 35 miles of electric cable and shot-hole wire. The cost from first to last was £70,000, The whole operations were carried on in all weathers, fair and foul, without interfering in any way with the continuous day and night traffic of the river, which, during the five years the work extended over, was confined to one or other half of the channel, and amounted to 180,000 vessels, with a tonnage of 33,000,000 tons, and included the largest steamers (at that time) afloat—the City of Rome, the Umbria, the Etruria, and the Russian ironclad, Peter the Great, being among the number.” TESTING DETONATOR FUSES. Testing Low-tension (Platinum) Fuses.—Care must be exercised when testing Platinum Fuses to put the Fuse several inches into an iron pot, pipe or other suitable receptacle before connection is made with the Galvanometer. When this is done the fuse wires should be con- nected with the terminals. If the Needle moves, the Fuse is good; but if it remains stationary, the Fuse is not to be relied upon. When the Bell - Galvanometer is used, the ringing of the bell indicates that the Fuse is good; if it fails to ring, the Fuse is defective. The Galvanometer must stand on a firm base, and must not be shaken when in use. Only one Fuse should be tested at a time, the rest being kept in some safe place during the opera- tion. Each Fuse, after being tested, should be put away in a box or cupboard in order to minimise risk. High-tension Fuses cannot be tested in this way. When ordering Fuses separately, it is necessary to state whether the exploding machine used is a high or Zoa/-tension one. PREPARING THE EXPLOSIVE. Most Nitro-Glycerine compounds are, when the temperature is below even 45 deg. Fahr., liable to congeal or become hard from the effect of cold. In this condition they should not be used until they have been carefully softened or thawed in a warming pan specially con- o 04