106 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[April, 



Mr. Harrison believed, that a scaffolding of a somewhat similar 

 construction was used by Messrs. Rennie, at the Victualling-yard at 

 Plymouth, in 132G. 



Mr. Rennie said, that the scafTolding employed for raising the statue 

 and other heavy parts of the worli, at the Victualling-yard, was on the 

 derrick principle, and was somewhat similar to that used for erecting 

 the Commemoration Column at Devonport, fig. 3. 



Mr. Grissell stated, that when writing the account of the scaffold- 

 ing at the NelsonColumn, that which had been used by IMessrs. Cubitt, 

 at the entrance of the London and Birmingham Railway, had entirely 

 escaped his recollection ; he now remembered it perfectly, and was 

 happy to have the opportunity of acknowledging that fact. He could 

 not speak too highly in praise of the system, and he thought its ad- 

 vantages had, as yet, been underrated. The waste of timber was 

 comparatively nothing ; while serving as scaffolding it was becoming 

 seasoned, and like that at the Nelson Column, could be immediately 

 worked up, in situations demanding dry timber. The cost was one- 

 half, and sometimes one-third, of the ordinary kind of scaffold, if the 

 loss by the rotting and destruction of poles and cords was taken into 

 account. The saving of labour in raising the materials was very great, 

 particularly where weights of from 8 tons to 14 tons required to be 

 lifted. If steam power had been used at the Nelson Column, a still 

 greater saving would have been effected. Another considerable ad- 

 vantage was the freedom from danger to the workmen ; during five 

 years, in all the works where he had used this kind of scaffolding, 

 only one man had been killed. That accident occurred at the Wool- 

 wich Graving Dock, when a man was thrown from the travelling car- 

 riage, by the handle of the winch striking him, from his having omitted 

 to put on the break. He believed that this description of scaff'olding 

 might be safely carried still higher than at the Nelson Column, for 

 although before the statue was hoisted, he had felt sometimes anxious, 

 and had thought of attaching guide chains, and using other precau- 

 tions, the fabric had stood so well, that he should not now hesitate to 

 go to a greater height, relying upon the scaffolding alone. 



Mr. Smith had adopted the system of the travelling winch on a 

 framing, with great advantage in his carving room, for moving the 

 heavy blocks of stone, from which the capitals of the columns for the 

 Royal Exchange were cut. Without such mechanical assistance, he 

 could never have executed his task within the required time, nor 

 could the capitals have been raised and placed on the carriages, to be 

 conveyed away, without much danger of injury. 



Mr. Giles said, that Corby Bridge, over the Eden, on the line of 

 the Newcastle and Carlisle Railway, was built by Mr. Denton, the 

 contractor, by mea.ns of whole timber scaffolding put together in three 

 stages. The bridge consisted of five arches, of SO feet span each, 100 

 feet in height, and contained 400,000 feet of stone-work, which was 

 executed with the greatest facility, chiefly owing to the convenience 

 afforded by the scaflfolding, and without any accident, excepting to 

 the foreman, who fell twice from a considerable height, but fortu- 

 nately was not killed. 



Mr. Fowler said, that the scafTolding at the Cathedral at Cologne, 

 was of whole timber; there was little doubt, that the system was very 

 similar to that which was employed, when the building was com- 

 menced in 1248. The crane which was used in raising the materials, 

 still remained on the summit of one of the towers; it was once re- 

 moved, but was speedily restored to its situation, as the superstitious 

 fears of the inhabitants of Cologne were excited by the occurrence of 

 a storm, immediately consequent upon the removal of the crane. It 

 had subsequently been constantly repaired as it decayed, so that at 

 present little of the original remained, but the form was still the same. 

 He believed that the materials for the York Column (Carlton Terrace) 

 were raised by a kind of travelling carriage, on the top of the scaf- 

 folding. 



Mr. Hawkins observed, that the scaffolds used at Vienna, for the 

 erection of any building of importance, were always constructed of 

 whole timbers, secured together by " dogs." In 1827 he superin- 

 tended the erection of an extensive sugar-house at Vienna, where 

 such scaffolding was used. 



Mr. CoLTHURST stated, that at Devonport there was a column built 

 of granite from Holman's Hill Quarry, near the Tamar. The shaft 

 was 11 feet in diameter ; its height, from the bottom of the shaft to 

 the top of the capital was 65 feet 4 inches. The total height of the 

 column, with its inferior and crowning pedestals, was 101 ft. 4 inches. 

 Its height above the street, including the rock on which it stood, was 

 124 feet. The abacus of the capital was composed of four stones, 

 each weighing between 3 and 4 tons. The stones of the column were 

 raised and set, entirely without the use of scaffolding, by means of a 

 series of tall spars joined together, fig. 3; the lowest being fised into 



the ground and braced by diagonal pieces, was lashed and strutted to 

 the lower part of the shaft. A gaff, with a jaw at the lower end, was 

 then slung in the throat by a strong rope or chain, so as to work round 

 the upright spar, in the jaw prepared for this movement ; from the 

 end of the gaff, blocks and a fall were suspended, in such a manner as 

 to command every part of the work, by raising or depressing the point 

 of the gaff", to increase or diminish its range. Crab winches sufficed 

 to raise the stones ; and it was stated that the work was executed in a 

 very short time. 



Mr. Rendel had seen this column while in course of construction; 

 the derrick appeared to act well ; and it was certainly a cheap mode 

 of raising the materials, 



Mr. Smith said, that in a recent visit to Liverpool, he had observed 

 an ingenious mode, adopted by Mr. Tomkinson, for raising building 

 materials, which almost superseded the use of external scaffolding. 

 It consisted of a very high double " derrick," placed upon wheels 

 running on a tram-way, laid parallel with the walls of the building; 

 the head of the derrick curved over towards the wall, and steam power 

 was employed for raising the materials, which appeared to be accom- 

 plished with rapidity. 



The President remarked, that the Institution always viewed with 

 pleasure, papers descriptive of the methods adopted by contractors, 

 in the execution of works designed by Civil Engineers or Architects. 

 The profession was much indebted to the practical skill and intelli- 

 gence of the contractors, and it would be extremely interesting, to 

 find recorded in the Minutes of Proceedings of the Institution, the 

 names of the inventors, and the dates of the introduction of such 

 ingenious modes of accomplishing works of magnitude, as had been 

 described by Messrs. Grissell and Peto. This could only be arrived 

 at by either the engineers or the contractors sending the necessary 

 information, or by their giving it during the discussions at the meet- 

 ings. 



General Pasley described the method adopted by Mr. T. Slacks 

 (Langholm), for building the obelisk which was erected on the Whitaw, 

 Eskdale, to the memory of the late Major-General Sir John Malcolm, 

 a native of that district. The obelisk, which was of white sand-stone, 

 was carried np to the height of 100 feet above the foundation; it was 

 built hollow, with thorough courses at intervals; through the centre 

 of each of these courses was left a circular hole, fig 4. In the lower 

 of these holes, was placed the foot of a pole 40 feet long, and 10 inches 

 diameter; the next hole above served as a stay, whilst the upper one 

 supported the whole weight, as around the pole was firmly fixed a 

 collar D, of hard wood. Beneath this collar 17 metal balls, 3^ inches 

 in diameter, were introduced, which, running in corresponding circular 

 grooves in the collar and the thorough course, enabled the pole to re- 

 volve easily. Across the top of the pole was mortised a beam 12 feet 

 long and 12 inches square, in the form of the letter T, and it was 

 strengthened by diagonal iron braces and straps. By means of a crab 

 winch B, with a rope passing over pulleys in each end of the trans- 

 verse beam, the stones, as at A, were raised to the requisite height, 

 and by a traversing carriage E, on the beam, a small crab C, and the 

 pulleys F, the stone was enabled to run inwards to the spot for laying 

 it. The crane was raised as each bond or thorough course was fixed, 

 and the time consumed in the operation of moving it did not exceed 

 two hours. This crane had been found very eflScient, and had greatly 

 reduced the cost of building the obelisk, which was completed in less 

 than twelve months. For the ingenuity displayed in this simple mo- 

 dification of the balance crane used by Mr. Stevenson, at the Bell Rock 

 Lighthouse, and for a clever hanging scaffolding used for completing 

 the pyramidal top of the obelisk, the Gold Isis Medal was vote.i to 

 Mr. Slack, by the Society of Arts, in 1836-7. 



A model was exhibited, of a moveable derrick crane, fig. 5, which 

 had been presented by Mr. Howkins. It was used by Mr. Wightman 

 at the works of the Granton Pier, Edinburgh, and was stated by him 

 to be very superior to any other kind of crane. It consisted of a ver- 

 tical post, supported by two timber back-stays, and a long moveable 

 jib, or derrick, which was hinged against the post below the gearing; 

 this jib was held by a chain, passing from a barrel over a pulley at the 

 top of the post, in such a manner that the extreme end of the jib viou^4 

 be raised almost vertically, or be lowered nearly to a hcviiontal posi- 

 tion. The chief advantage it possessed over the oid gibbet crane was,^ 

 that it commanded concentric circles of from 10 feet to GO feet radius, 

 which was of great use in large works, as it could extend its sweep 

 over a circle of 120 feet diarr-eter, without being moved from its posi- 

 tion ; whereas, the eld gibbet crane commanded only one circle of I i 

 comparatively limited extent, and in moving it, as the works proceeded, 

 there was a considerable loss of time. 



Mr. Bremner stated, that he had seen the crane at Granton Pier ; [ 

 it was a very useful machine, and the only fault he could find, with i^ 



