1842. 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



.351 



where heavy masses such as parts of machinery required to l)e moved about 

 — he would always adopt the system in constructing a manufactory. 



Mr. Smith observed that an arched roof would be found as cheap as one 

 of wood and slates, and in the relative dural)ility there could be no com- 

 parison. 



Mr. Marshall desired it to be home in mind that the cut stone front of 

 the mill had greatly enhanced the cost, and that being the first building of 

 the kind erected in the neighbourhood of Leeds, it had naturally been more 

 expensive than others would be. 



" Account of the Explosion of a Steam Boiler at the Penydarran Iron 

 Works, South Wales." By Adrian Stephens. 



The boiler, the explosion of which is described in the paper, was one of a 

 pair for furnishing steam to a high-pressure engine, with a cylinder of 26 

 inches diameter, working expansively, tlifi steam being cut otf at half the 

 stroke ; each of these boilers was 4 1 feet long, and 7 feet diameter, with a 

 centre tube flue of 4 feet 2 inches diameter ; the thickness of the plates 

 throughout was J inch ; the ends were flat, with rings of angle-iron, and 

 the pressure of the steam to wliich the safety valves were weighted was 

 501h. on the square inch. From appearances after the explosion, it was con- 

 jectured that the tube, which was collapsed in a remarkable manner in its 

 entire length, had been softened by the heat, having probably been left dry 

 along the upper side. No opinion is given as to the cause of the explosion, 

 but it is particularly mentioned that the supply of feed-water depended upon 

 the regular attention of the engineer, and that the feed-pipe was placed so 

 that the water fell directly upon the hottest part of the tube flue, and it is 

 remarkable that the tube is most extensively fractured at that spot. All 

 the appearances presented by the boiler botji'before and after the explosion 

 and the injury done by the event are accurately detailed, and the paper was 

 illustrated by a drawing of the boiler and the setting. 



STONE BORING MACHINE. 



Mr. Carnegie presented one of Hunter's Stone Boring Machines to the 

 Institution, and explained its action to the meeting. 



The raachuie is composed of two parallel bars of steel, supporting a 

 traversing carriage, through the centre of which passes a spiral auger at- 

 tached to a screwed bar ; this bar (its into a female screw clamp above the 

 carnage, and on the upper end is a winch with four handles. When the 

 ins rument is in use it is fixed by two cramps ui)on the stone to be pierced, 

 and the auger being made to revolve by means of the winch, scoops out at 

 each revolution as great a depth of stone as is equal to the distance which 

 the screw descends ; the chips ascending through the spiral channel of the 

 auger, are thrown off- at the top. The peculiar shape of the point of the 

 auger prevents its being abraded, as it operates by chipping the stone, and 

 not by grinding It away. This, with the means of forcing it down by the 

 screw, IS the chief novelty of the machine. It has been extensively used at 



the works of the new Harbour of Arbroath, by Mr. Leslie, who speaks of it 

 in the following terms : — 



" Mr. Hunter's Boring Machine has been advantageouslv emploved for 

 above a year, in boring trenail holes in the stones used at the new Harbour 

 of Arbroath. The holes are )} inch diameter, and from 9 inches to 2 

 feet in depth : the aggregate of the holes already bored amounts to upwards 

 of 30,000 linear feet. The macliine may be adopted for boring holes of 

 any dimensions. It does the work considerablv cheaper than the "jumper," 

 and much more correctly, as it makes the holes perfectly straight, cvlindri- 

 cal, and equal throughout, instead of the irregular form made bv tlie com- 

 mon jumper. This machine is very well adapted for boring railway blocks, 

 and has been much used in this quarter for that purpose. I consider it to 

 be more especially valuable from the facility which it atfords of boring and 

 trenailing down the stones used in sea buildings in any exposed situation, as I 

 have found that trenailing is a great security to such building while in pro- 

 gress, when the upper courses are much exposed and liable to be washed off 

 unless they be held down by other means than their own absolute weight. 

 The expense of boring the old red sandstone rodi, here, is about three half- 

 pence per hnear foot. 



Remarks. — Mr. Vignoles bore testimony to the advantages of the machine : 

 he was now employing it for piercing holes in stones going from Arbroath to 

 the West Indies for the construction of a patent slip — there was great eco- 

 nomy of cost and time by its use in addition to the superior manner in 

 wliich the holes were made. 



Mr. Smith, of Deanston, was convinced of the advantage of the machine 

 in working almost all kinds of stone, but more especially for those resem- 

 bling the Arbroath stones, which were from a bed beneath the old red sand- 

 stone : they were of fine grit mingled with schistose debris. The action of 

 the tool was like that of the stone-planing machine, to burst cliips off in- 

 stead of grinding down the surface by small portions and destroying the 

 edge of the tool at the same time. With the planing machine it was common 

 to take off a thickness of 3 inches at one passage of the tool — it acted hke 

 a '- pick ;" and being fixed in a frame weighing about Ij ton, the power was 

 great ; at the same time there was little abrasion of the tool and it never 

 became heated or softened. It was probable that with other qualities of 

 stone a screw with another pitch of thread might be required to force the auger 

 forward, but with the thread now used in boring stones from the Arbroath 

 quarries, the economy of time and cost appeared very great. In each of the 

 blocks for the Arbroath railway it was requisite to bore two trenail holes 

 li inch diameter and 6 inches deep— and to level a space 9 inches diameter 

 to receive the cast-iron chair : this had been contracted for at twopence 

 halfpenny per block, which was a material diminution of the usual cost. 

 He was convmced that the instrument only required to be known to be 

 extensively used. 



Mr. F. Braithwaite had for some years used Hunter's stone-planing ma- 

 chines, for dressing up slate and other stones, and was well qualified to give 

 a favourable opinion of the principle of its action : he believed that the 

 machine under discussion being upon tlie same priuciple must he verv useful. 



May 24. — The President in the Chair. 

 " On the machinery used for working the Diving Bell at Kingstown Har- 

 hour, Dublin." By Peter Henderson, Assoc. Inst. C. E. 



After referring for the details of the machinery to the two drawings which 

 accompany the paper, the author describes the foundations of the pier bead 

 to have been laid in a depth of 20 feet at low water on rock and firm sand. 

 For 14 feet from the bottom, the wall is formed of Runcorn sandstone of fine 

 quality, each stone containing about 50 cubic feet and thoroughly squared. 

 This has been preferred to granite on account of its cheapness and the fa- 

 ciUty with which it is worked under water. After the foundation course is 

 secured, from 300 to 350 cubic feet of this walling are frequently set in a 

 perfect manner by the diving-bell during a fair working day of eight hours. 

 The first stone was set on the 5th of August, and by the 1st of January 

 16,000 cubic feet had been laid. From 6 feet below low water to the coping, 

 it is proposed to make use of granite in blocks of 50 cubic feet each, which 

 is procured cheaply and in abundance in the immediate neighbourhood. The 

 piers are finished in the interior by walling of rubble stone carefully laid. 

 For the purpose of forming this excellent harbour, an area of 251 acres has 

 been inclosed between two substantial stone piers ot 8,340 feet in length, 

 affording clear anchorage in a depth of water from 15 to 2" feet at low spring 

 tides. The interior shows no natural tendency to collect deposiis likely to 

 reduce the depth of water, nor do any of the works exhibit symptoms of de- 

 terioration, while its continual occupation by vessels of every description, 

 together with the comparative freedom from accident in Dubhn Bay, afford 

 convincing proof of its great utility. 



" Description of a S/eam Dredging Engine used upon the Caledonian Canal." 

 By Walter Elliot. 



The machine described in this communication is not remarkable as being 

 of the most perfect description, hut as it is stated to be among the earliest 

 which were brought into use in this country, a certain degree of interest is 

 attached to it. It was constructed in the year 1814 expressly for the for- 



