1T6 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



fJuNE, 



posed to wilhholJ tlieir sympatliy from the heartfelt expressions of gratitude 

 which often went round our little circle in the boats, as we rowed in the 

 twilight from the rock to the ship. Isolation from the world, in a situation 

 of common danger, produces amongst most men a freer interchange of the 

 feelings of dependence on the Almighty, than is common in the more chilly 

 intercourse of ordinary life. 



With a view to lessen the dangers of hlasting in such a situation, I had 

 provided a galvanic battery on the plan proposed by Mr. Martyn Rol)ert3, 

 but I used it less frequently than I intended. The attachment of the wires 

 were very liable to be broken from various causes, where there were many 

 men congregated in a small space; and as we could not venture to leave the 

 apparatus on the rock, the frequent re-shipment of it in a heavy sea was 

 another cause of the derangement of its parts. I soon, therefore, laid it 

 aside, and only had recourse to it when any work was to he done uiuler 

 water, or in cases where the simultaneous firing of several mines (for which 

 it is admirably adapted) was of importance in elfeciing any special purpose. 



When the floor had been roughly levelled I again carefullj surveyed the 

 rock, with the view of fixing precisely the site of the foundation-pit, and of 

 caking advantage of its form and structure to adopt the largest diameter for 

 the lower of which the rock would admit. In some places I found that 

 parts of the rock, apparently solid, had been undermined by the constant 

 action of the waves, to the distance of l.'i feet inward from its face ; but none 

 of those cavernous excavations reached the main nucleus, so that, after much 

 deliberation and repeated examinations of all the veins and fissures, I was 

 enabled to mark out a foundation-pit 42 ftet in diameter, on one level 

 throughout. That was a point of no small importance ; and although it had 

 cost great labour at the very outset, much time was saved by it in the sub- 

 sequent stages of the work. Not only was the labour thereby avoided of 

 cutting the rock into separate terraces, and fitting the blocks to each suc- 

 cessive step, as was done by Smeaton at the Eddystone ; but the certainty 

 that we had a level foundation to start from, enabled us at once to commence 

 the dressing of stones without regard to any irregularities in the surface of 

 the rock ; and the building operations, when once commenced, continued 

 unimpeded by the necessity for accommodating the courses to their places in 

 the foundation-pit, so that the tower soon rose above the level, at which 

 there was the greatest risk of the stones being removed by the waves before 

 the pressure of the superincumbent building bad become great enough to 

 retain them in their places. 



The outline of the circular foundation-pit, 42 feet in diameter, having been 

 traced with a trainer on the rock, numerous jumper-holes were bored in 

 various places, having their bottoms all terminating in one level plane, so as 

 to serve as guides for the depth to which the basin was to be excavated. 

 The depth did not exceed 15 inches below the average level, already laid 

 bare by the cutting of the rough horizontal floor which has just been 

 described ; and before the close of the season of 1839, about one-t/iird of the 

 area of the circle had been cleared, and was ready for the final pick-dressing 

 which prepared it for the reception of the first course. The excavation of 

 this circular basin was conducted with the greatest caution, and few shots 

 were permitted to be fired lest the foundation should in any place be shaken 

 by the action of the gunpowder on any of the natural fissures of the rock. 

 The work was chiefly done by means of what are called plugs and feathers. 

 In that part of the work the bores were nearly horizontal, and the action of 

 the plug and feathers was to throw up a thin superficial shelf or paring of 

 rock of from 6 to 12 inches in depth, and not more than 2 feet square. By 

 tliat painful process an area of about 1,400 superficial feet was cleared. The 

 thief trouble connected with that operation was cutting, by means of the 

 pick, a vertical face for the entrance of the Lorizontal^'«m;)ers or boring 

 rods ; and wherever advantage could be taken of natural fissures it was gladly 

 done. Another considerable source of labour was the dressing of the vertical 

 edges of the basin, as that implied cutting a square check, 15 inches deep 

 and about 130 feet long, in the hardest gneiss rock ; and the labour attend- 

 ing which, can only be fully estimated by a practical stone-cutter who has 

 wrought in such a material. The plan employed was to bore all around the 

 periphery of the circle, IJ inch vertical jumper-holes, 6 inches apart, to the 

 required depth, and to out out the stone between them. The surface thus 

 left was afterwards carefully dressed, so as to admit vertical and horizontal 

 moulds, representing truly the form of the masonry which the check was in- 

 tended to receive. The experience of the labour attending that operation 

 gave me great reason for congratulation on having adopted a foundation on 

 one level throughout, instead of cutting the rock into several terraces, at 

 each of which the same labour of cutting angular checks must necessarily 

 have been encountered. The cutting of the foundation occupied 20 men for 

 217 days in all, whereof 1G8 days were in the season of 1839, and the rest 

 in the summer of 1840." 



It was not till 1840 that this pit was finished, when Mr. Steven- 

 eon says — 



" The rock, indeed, was in many places so hard as often to make it seem 

 hopeless that tools could make any impression on it. The time employed in 

 the excavation and the number of tools expended on it, were very great, as 

 a pick seldom stood more than three strokes in the harder quartzose veins ; 

 but our perseverance was at length amply rewarded by obtaining a founda- 

 tion so level and so fairly wrought throughout the whole area of a circle 42 

 feet in diameter, as to present to the view the appearance of a gigantic basin 

 of variegated marble; and so much pleased were the workmen themselves 

 with the result of their protracted toil, that many of them expressed serious 



regret that the foundation must soon he covered up, so as (we trusted) 

 never to be seen again. In the dressing of the rock much inconvenience 

 arose from the small splinters which flew out before the tools, sometimes 

 rising to the height nf 40 feet, and coming in at the windows of the barrark ; 

 and after several injfiries had been sustained, I at length found it necessary 

 to send tn Glasgow for fencing masks to protect the men's faces. In ail our 

 work, nothing was more grudged than the occasional loss of half a day in 

 baling out the water from the foundation-pit after it had been filled by a 

 heavy sea." 



The mortar einployed in the building was composed of equal 

 parts of Aberdda lime and Pozzolano earth, being identical with 

 tliat used by Smeaton. 



In 184-0, six courses were set, being a mass of masonry equal to 

 the whole of the Eddystone tower. In 1841, 30,300 cubic feet were 

 built, being twice as much as the Eddystone, and more than the 

 whole Bell-rock lighthouse. In 1842, the masonry work was 

 finislied. 



The general arrangement of the tower is much like that of the 

 BeU-rock lighthouse. 



"The ascent to the outside door is by a ladder or trap of gun metal, 26 

 feet high. The first apartment on the level of the entrance door, is chiefly 

 appropriated to the reception of iron water-tanks, capable of holding a 

 supply of 1251 gallons. The next story is set aside for coals, which are 

 stowed in large iron boxes. The third apartment is a workshop ; the fourth 

 is the provision store; and the fifth is the kitchen. Above are two stories, 

 each divided into two sleeping apartments, for the four light-keepers. Over 

 them is the room for the visiting officers; then follows the oil store, and 

 lastly comes the lightroom. making in all twelve apartments. The nearness 

 of the oil store to the lightroom is a great convenience to the keepers, 

 who are thus saved the trouble of carrying the daUy supply of oil to the 

 lightroom, up a long flight of steps. The passage from story to story is by 

 oaken trap ladders, p.-issing through hatches in each floor and partitioned otf 

 from each apartment in order to prevent accidents and to check cold 

 draughts." 



The light was exhibited at Skerryvore on the 1st of February, 

 1844. 



The whole cost of erection was 90,268/. 12*. Id., but of this very 

 little was spent directly on the lighthouse. The cost may be thus 

 subdivided : — 



Establishment at Hynish .. .. £4822 



Rock barrack. No. 1 .. .. .. 790 



No. 2 .. .. .. 1479 



Establishment and quarries at North Bay .. 1883 



Signal tower and lights at Hynish .. 1215 



Wharf and railway at Skerryvore .. 257 



Steamer, tender, and stone Hghters .. 17145 



Moorings .. .. .. .. 766 



Boats and freight of hired vessels .. 5700 



Labourers discharging cargoes .. .. 933 



Travelling expenses .. .. .. 1711 



Coals .. .. .. .. 1463 



Gunpowder .. .. .. .. 375 



Excavating platform .. .. .. 763 



Dressing lighthouse blocks .. .. 9929 



Tools and machinery .. .. .. 4267 



Cartage .. .. .. .. 1104 



Mortar .. .. .. .. 889 



Lighthouse tower, putting together and fittings 8551 



Lightroom .. .. .. .. 3851 



Salaries . . . . . . ■ . 3656 



Ligbtkeepers' houses .. .. .. 3915 



Pier at Hynish .. .. .. 2591 



Dock at Hynish for the tender .. .. 7055 , 



From the whole cost, 2,839/. is to be taken off for the steamer 

 and materials sold, but each item is given by Mr. Stevenson in 

 detaO. 



Having thus followed Mr. Stevenson throughout his labours on 

 the tower at Skerryvore, we must keep until next month our 

 remarks on a subject no less interesting — that of lights, to which 

 a great part of his book is devoted. 



EledHe Telegraphs. London : Bog^e, 1848. 



This is a shilling volume of scraps for the railway carriage, 

 which contains more information about the Electric Telegraph, 

 and more amusement, than any which has yet been published. 

 There is not an invention in England, the United States, or abroad, 

 which has escaped the author's attention. 



