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

AN EXAMPLE OF ROCK DRILLING BY DIAMOND DRILLS WORKED BY STEAM ENGINES. We quote an extract from a paper read at the Institute of Naval Architects, describing the removal of the rock in deepening the River Clyde and the means adopted, viz. :— “ Any history of the improvement of the river would be incomplete if reference were not made to the removal of Elderslie Rock, a huge vein of trap which extends across the river a short distance above Renfrew. In the early reports on the condition of the Clyde no men- tion is made of this rock, but the Blawarthill Sand, one of the many shallow fords on the river, was situated where the rock was subsequently found, and in 1755 there was a depth on this sand of only i8in. at low water, and 4ft. gin. at high water. It was not till 1854 that the existence of the rock was discovered by the grounding on it of the Glasgow, one of the first steamers trading between Glasgow and i\ew York, which, while passing up the river, knocked a hole in her bottom on the rock. It was at first thought it might be a large boulder that had done the damage, but borings showed that it was lock, that it extended over an area of the bed of the river 925ft. in length by about 320ft. in breadth, and that it was a hard whinstone or trap dyke. From the time of its dis- covery till the beginning of 1869 boring from a movable stage and by diving bell and blasting with gunpowder, had given a minimum depth at low-water springs of 14ft. for half the width of channel, and a minimum depth of 8ft. to the other half, the total width of the river theie from bank to bank being only 410ft., at an expenditure of upwards of ^16,000; but it was not until 1880 that the removal of the rock., so as to give a uniform depth of 20ft. at low-water springs over every poition of the channel, was commenced with diamond drills. “ I he boring was done in longitudinal belts, in sections of five rows of holes transversely, by 40ft. long ; the holes were transversely 5ft. apart centres, and so that the holes longitudin- ally would be opposite one another in each alternate row. Eight holes longitudinally were bored simultaneously, then charged and blasted, and the other four rows dealt with in the same way. \\ hen all the five rows in the section had been bored, charged and blasted, the boring barge was shifted up-strèam and commenced operations on the next 40ft. long section, and an ordinary but powerful single-ladder small bucket dredger following, lifted the broken rock and left an open space for the next belt of holes. “ It was early found that where the depth of hole was more than 10ft., the rock was not sufficiently disintegrated to enable the dredger to clear it freely away to the bottom of the holes, and the deeper portions of the rock were therefore taken in two depths or breaks, the first depth being bored to 17ft. at low water, blasted and dredged. I he longitudinal belts of holes were continued fiom the south side, outwards, into the middle of the river until the whole ground in the southern half was cleared away to 20ft. at low water, the whole up and down traffic being meantime confined to the north half of the river. The whole traffic was then diverted from the north into the new south channel, which was marked by three of Pintsch’s compressed gas-lit buoys, capable of burning- for three months continuously. The operations were then continued northwards until the whole depth of the river bed was cleared to 20ft. depth. “ The explosives used were Nobel’s Dynamite and Blasting Gelatine, Tonite and Potentite. Dynamite was found most satisfactory ; Blasting Gelatine proved the most powerfu explosive, but when frozen was more dangerous to handle and more difficult to explode thoroughly. Tonite and Potentite were found to be somewhat less powerful than Dynamite. “Two horizontal engines on the deck of the boring barge, supplied with steam from two boilers, drove the eight drills by a main shaft which extended the whole length of the barge. 102