THE GUNPOWDER PILE DRIVER.

Waikato Times, Volume IV, Issue 215, 25 September 1873, Page 2

THE GUNPOWDER PILE DRIVER.

(From Engineering for March.) AaiO'Cr the many useful improvements introduced of late years in connection with labour-saving apparatus for engineering co atruchon may certainly be classed the gunpowder pile-driver of Messrs Shaw and Justice. Brought out originally in the United States, it was introduced into England some five years since, and its working has demonstrated that bj its uw a considerable saving is effected both m lime and costs as against the ordinary method of pile-driving. The apparatus will be found described and illustrated nt page 79 of our eighth volume, so tliut u brief referencs to its principle will be sufficient hero. It consists of an ordinary pile•Jriving enginn having a ram, from the upper and underside of which a plunger project* 'Jhe ram is fitted with an nrrangement by which it may be retained at any desired height above the pile-head. A cast-iron cap, having a bole in its centre into which the lower plunger ol the mm will fit, is plmvd on the top of the pile to be driven, and in the hole is inserted a small charge of gunpowder. On the ram being relcastd the lower plunger enter* the hole in the cap, com-pres-ung the air within generates heat, which ignites the gunpowder. The force of the explosion is utilised partly in driving the pilo downwards, and partly in throwing the ram upwards., the latter being detained at the required height ready for the next blow. Should the ram be thrown too high, the upper plunger enters an air cylinder, compresiing <he air and cushioning the blow The charges of gunpowder j were at first fed into the cap-piece by hand, but a sell-acting feeding arrangement was afterwards added which still simplifies its operation. Some experiments in pile-driving were successfully carried out with one of these machines at Hamilton's, Windsor Iron Works, at Garston, in the presence of a number of gt ntlemen interested in such operations. A very fair idea of the pel formance of these machines on a practical scale may be gathered from the report of the United States engineers on work done in the JJavy Yaid, Lpague Island, rather more than a j ear since. A bout 400 piles were driven mainly from a ecow or barge on which the apparatus was erected. Very low tides, severe cold, heavy ice, and sunken rocks rendered the work of driving somewhat difficult, but notwithstantl'iig this the retult was that the 400 piles,, aveiaging over thirty feet in length and ten inches in diameter, were driven an average depth of twentyone feet each in an average time of thiiteen and a-half minutes per pile, inclusive of moving the barge into position. The a\eragp number of bows to each pile was eight and a half and the average distance to eai-b blow nas tvo <cet «s inches The piles were driven without rings, shoes, or points, cm h pilo being cut off square at top and bottom but not one is reported to have split or splintered. The charges used were one and one and a quarter ounces of common blasting powder compressed into cylindrical blocks, and rendered non-explosive except at high temperatures. The results show that the desideratum of preserving each pile solid and unbhatteied is attained by the gunpowder driver. Of the evpurmmits at Garston we may have more to say ueitweck

It is jtioj oseil to construct a new graving (lock at lii'iilu.ul, Lun.i.slmr, .«t a u>st uf dLIoO.OOO.