1849.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



79 



and afterwards until the breaking up of the working establishment 

 and sale of the stores at Arbroath. (See Mr. Stevenson's letter of 

 8th July, 1811, and Mr. Rennie's answer on the I5th following.) 



From the above statement of facts the following conclusions 

 may, I think, be fairly drawn: — First, that Sir Ale.xander Coch- 

 rane was the first who suggested the idea of erecting a lighthouse 

 upon the Bell Rock. Secondly, that Captain Brodie and Mr. 

 Couper, were tlie first who took up the subject prnctically^ by 

 erecting a beacon and preparing a model for a cast-iron light- 

 house. Thirdly, that Mr. Robert Stevenson commenced his inves- 

 tigation in 1791, and in 1800 made two models, one for a cast- 

 iron, and another for a stone lighthouse, upon the principle of the 

 Eddystone. Fourthly, in 1803, when the Commissioners of the 

 Northern Liglithouses took this subject up seriously, and went to 

 parliament for a bill to enable them to borrow money for the pur- 

 pose, they feeling tlie weight of the responsibility and trust rejiosed 

 in them, naturally determined to consult an older and more expe- 

 rienced engineer than Mr. Stevenson then was. Mr. Telford was 

 accordiugly consulted, but it does not appear that he either made 

 a design or Report on the subject, although no doubt he gave much 

 valuable advice. After, however, the rejection of the bill in 

 1803, Mr. Telford was not again consulted. Fifthly, in 1805, 

 when the Commissioners determined again to apply to parliament 

 for an Act to make a lighthouse on tlie Bell Rock, they consulted 

 the late Mr. Rennie, and submitted Mr. Stevenson's designs, as 

 well as the various other documents which had been prepared for 

 that object. Mr. Rennie accordingly personally inspected the 

 Bell Rock, and made a detailed and elaborate Report upon the 

 whole subject, wherein, amongst other matters, he did not appro\e 

 of Mr. Stevenson's designs, as stated in the foregoing part 

 of this letter. Mr. Rennie then continued in the employment of 

 the Commissioners, and attended and gave evidence upon the hill 

 in its progress through parliament in 1806; and as soon as prac- 

 ticable after the passing of the bill, a meeting %vas held by the 

 Commissioners on the 3rd of December, 1806, at which he at- 

 tended, and was appointed chief engineer to carry it into eifect; 

 and on the 26th of the same month, another meeting was held, 

 when Mr. Rennie recommended that Air. Robert Stevenson should 

 be appointed assistant engineer, to act under his (Mr. Rennie's) 

 directions ; and Mr. Robert Stevenson v>ns appointed assistant en- 

 gineer under Mr. Rennie accordingly. That subsequently to that 

 period, until the completion of^ the lighthouse and the final 

 winding-up of the establishment, Mr. Rennie continued to have 

 the entire responsibility, superintendence, management, and di- 

 rection of the whole worlvs: he furnished a design and worked out 

 the details, which were completed under him — in fact, nothing was 

 done without previously being submitted to, and receiving his ap- 

 proval; that he repeatedly visited the woi-ks and made his Reports 

 to the Commissioners during the progress until the final comple- 

 tion, as will be seen in the Appendix to Mr. Stevenson's book, 

 together with the other documents in my possession. The design 

 which has actually been carried into effect underwent certain al- 

 terations, differing somewhat from that furnished by Mr. Rennie, 

 and which generally happened during the progress of the work; 

 these were chiefly confined to raising the tower a little higher, and 

 altering the mouldings round the top of the tower and lantern. 

 These alterations, however, were done under his direction. The 

 lighthouse as erected, it wiU be observed, differs materially from that 

 proposed by ]Mr. Stevenson, which was not approved of by Mr. 

 Rennie : the base is much wider and different in form, in order to 

 diminish the action of the waves upon it, and to prevent them 

 from undermining the base; the tower is also much higher; the 

 courses, narrower on the outside, are larger towards the centre of 

 the building than that of the Eddystone, by which they are ren- 

 dered stronger; and the floois are different, the pressure being 

 rendered vertical instead of lateral, as explained in the above 

 extract from Mr Rennie's Report; — in fact, in the above particu- 

 lars the Bell Rock Lighthouse differs from the Eddystone, but 

 Mr. Rennie used always to say that he followed the track of 

 Smeaton in his fine example of "the Eddystone, making only such 

 alterations as the different circumstances required, to adapt it for 

 its situation. Mr. Alan Stevenson claims for his father the 

 merit of the improvement in the floors of the Bell Rock Light- 

 house, and making the pressure vertical instead of lateral, as in 

 the Eddystone: tliis, I cannot admit, — for in the paragraph above 

 extracted from Mr. Robert Stevenson's Report of the year 1800 

 (p. 445), the words there used do not convey the idea that the 

 lateral pressure of the floors was intended to be done away with ; 

 and it cannot be supposed for a moment that the late Mr. Rennie, 

 who disapproved of his plan, could have adopted it himself after- 

 wards, and have claimed the merit of it. The whole tenor of Mr. 



Rennie's conduct througliout his long career, was totally at variance 

 with such a proceeding, and it was always his greatest pleasure to 

 recognise and liring forward merit in every case, and to give the 

 inventor the full benefit of his inventions. I trust, therefore, 

 that I have clearly established my proposition — that Air. Rennie 

 designed and built tlie Bell Rock Lighthouse. In saying this 

 much, I should be extremely sorry to detract in the smallest de- 

 gree from the highly-meritorious exertions of Mr. Stevenson, for 

 the important part he took in forwarding the undertaking, from the 

 year 1794 to 1805, and for the subsequent part which he performed 

 as assistant-engineer in carrying the work into effect under the 

 late Mr. Rennie; and I am quite ready to admit that very great 

 credit is due to Mr. Stevenson for the energy, skill, and inde- 

 fatigable perseverance he displayed in the above capacity, and 

 which contributed materially to the success of this great work. 

 The labours of those valuable sub-officers, Mr. Peter and David 

 Logan and Francis Watts, were of the greatest service; and Mr. 

 DavidLogan subsequently distinguished himself as resident engineer 

 !it Dundee, Donhagadee, Port Patrick, Whitehaven, Port Rush, &c., 

 and finally closed his valuable career as engineer to the Trustees 

 of the River Clyde; and I cannot close this letter without adding, 

 that the greatest credit is due to the Commissioners of 'the 

 Northern Lighthouses, and their secretary, Mr. Cuningham, for 

 the public spirit, energy, and ability with which they brought for- 

 ward, and carried out to a successful conclusion, this important 

 maritime %vork, which has conferred such invaluable benefits upon 

 the shipping interest and commercial world. 



I am, 



Your humble servant, 



London, February Sth, 1849. John Rennie. 



P.S. Mr. Alan Stevenson complains, in a postscript to his printed 

 letter, of my want of courtesy in not replying to him. — The fact 

 is, I was absent on the continent, and did not receive his letter 

 until I returned some time after. 1 then immediately wrote to 

 him, apologising that absence had unavoidably prevented me from 

 replying to his letter before. 



HSGISTEK OF M£^V FATSNTS. 



COMPASSES, BAROMETERS, &c. 



David Napier and James jMurdoch Napiee, of York-road, 

 Lambeth, engineers, for '■'■improvements in mariners' compasses; also 

 in barometers, and in certain other measuring instruments." — Granted 

 July 20, 1848; Enrolled January 20, 1819. [Reported in the 

 3fechanics' Magasine.l 



The improvements sought to be secured under this patent, 

 relate — 1st, to mariners' compasses; 2nd, to barometers; 3rd, to 

 tachometers, or instruments for ascertaining the speed of \'essels 

 through water, or the velocity of currents of water; and 4th, to 

 weigh-bridges or platform weighing-machines. 



1. The compass-box is gimballed, as usual, and contains the com- 

 pass card, which is bound by a brass hoop, to which grip-pieces are 

 soldered. Above, and resting upon the needles, is a thin disc of 

 "talc-brass," to which is fastened a disc of cotton or velvet, or 

 other soft substance. A printed or ruled piece of paper, contain- 

 ing twenty-four concentric circles, and a number of radiating lines 

 corresponding with the points or parts of points in a compass- 

 card, is temporarily held in the grips above the talc-brass and soft 

 substance. Underneath the compass-card there are three branches 

 fixed to a loose collar on the spindle of the point, so that they 

 may be slid up and down to serve as abutments or supports to the 

 card. A lever is connected at one extremity with a vibrating 

 frame, and cari'ies at the other a vertical pricker, which is made 

 to travel over the surface of the paper from the inner concentric 

 circle to the outer one, and in a line parallel with the keel of the 

 vessel, once in twenty-four hours. The lever is made to rise and 

 fall, and consequently the pricker to puncture the paper at certain 

 regular intervals of time, and the branches to rise up and support 

 the card each time the puncture is effected. By this arrangement, 

 the direction of the ship's course will be indicated by the punc- 

 tures on tlie radiating lines, and the time by those upon the con- 

 centric circles. The lever, together with its pricker, and the 

 branches, are actuated by ordinary clock-work machinery, which 

 is carried in the bottom of the compass-box, by means of a pecu- 

 liar combination of toothed gear and levers. The printed paper 

 is, of course, changed every twenty-four hours. 



