108 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[April, 



M.Pierre Jouknet described "J Syslem of Scaffolding, employed 

 at Paris, /or the Repairs of Public Buildings, Obcliaks, ^c," 



fl 



Flj. 10, 



I 



Hi 



Upilglit Piece. 



Fig. U.-Bradiet. 



M. JouRNET considers that scafTolding may be divided into two 

 classes; the first to comprise the more substantial kinds, which are 

 employed in the erection of buildings and monuments; the second in- 

 cluding the temporary constructions, used for repairing, or decorating 

 the exterior, or interior of public buildings, dwellings, or monuments. 

 He contends that the usu.d method of constructing scaffolding with 

 poles, lashed together with ropes, is vicious and expensive, and is 

 attended with danger to the workmen. That such a system is not 

 necessary, but that scaffolding should be so constructed that the same 

 materials should always serve, without cutting and without the use of 

 ropes ; and that it should be composed of a number of similar pieces, 

 which should adapt themselves to every kind of building. Upon 

 these principles the author designed the scaffolding treated of in the 

 paper, in which he describes its more immediate application to build- 

 ing or repairing high chimneys for steam boilers, or other similar con- 

 structions. The distinguishing feature of the system is, that it acts by 

 pressure upon the building, and is supported by it as it rises, no up- 

 rights being fixed in the ground. 



In the case of the construction of a chimney (figs. 8, 9, 10, and 11), 

 at each side, if it be square, or at given distances around it, if it be 

 circular, are placed upright pieces of deal A, cut to equal lengths of 5 

 feet ; upon each of these is fixed a cleat B, with an entail C, at the 

 top ; four binding chains D, with screws at each corner, are braced 

 tight around the chimney at the bottom of the entails in the cleats; 

 into these entails, and hooked upon the irons at the end of the chains, 

 are placed the brackets, fig. 11, which support the scaffolding planks, 

 and at the same time the light railing for the safety of the workmen ; 

 all these pieces are made precisely similar. The workmen fix a fresh 

 set at every height of 5 feet, taking the set from below and fixing it 

 above, so tliat there are never more than two sets in use at the same 

 time, except those which are allowed to remain for forming stages for 

 the ladders. They are placed with great rapidity, and in descending 

 the men detach the uprights and binding chains, which have been al- 

 lowed to remain in order to consolidate the work, while the mortar 

 dried. The joints can be pointed as the scaffold is removed, and the 

 work can be carefully inspected by the engineer or architect, which in 

 the ordinary modes of construction is not possible. 



The author contends that this method is superior to the now usual 

 mode of constructing chimneys, by the workmen standing withinside, 

 upon a scaffold formed upon bars let into holes in the work, and which 

 obliges the men to lean over to do their work. In repairing chimneys, 

 obelisks, columns, &c., he has used it very extensively, and the saving 

 of expense is very considerable. 



This system has been adapted in Paris to the construction and re- 

 pairs, both external and internal, of dwelling-houses with much suc- 

 cess, and the author promises, on a future occasion, a description of 

 this application of the principle. 



"Repairing a chimney \2Q feet high, at the Cotton Mill of Measn. 

 Couper, Glasgow." By Joseph Colthurst, Grad. Inst. C. E. 



The way in which the tops of high chimneys have hitherto been 

 repaired has been, either by erecting an outside scaffulding to the full 

 height, or by incurring the, generally speaking, greater expense of 

 stopping the works and allowing the chimney to cool, and then sending 

 a man up the inside, who, by fixing spars across, is able to ascend to 

 the top. To avoid the expense and inconvenience attendant on both 

 these methods of proceeding, the author determined to adopt the fol- 

 lowing means: — The man engaged to ascend was furnished with a 

 broad leather belt, to which was attached a strong spring hook; lad- 

 der irons were next provided, of the form shown in the sketch A, fig. 

 12, and the man then proceeded to drive them into the joints of the 

 brickwork, at intervals of about 15 inches ; then standing on one, and 

 being hooked to that whicli was immediately opposite to his waist, he 

 ascended, driving the ladder-irons in, one above the other, until be 

 reached the top, from whence he removed some ornamental plates of 

 iron which had been loosened by a storm, and which it was expected 

 would be blown down on the buildings beneath by the next gale of 

 wind. The ladder-irons were taken out as the man descended. The 

 wdiole operation was performed in two days and a half, and would 

 have occupied less time, if the smiths could have furnished the ladder- 

 irons as quickly as they were required. 



To ensure tbe safety of the man employed, a rope was passed up 

 withinside all the ladder-irons, and was fastened to the belt round his 

 waist and to a pin driven into the base of the chimney; this rope was, 

 of course, payed out to him at each step as he ascended. It was also 

 intended, in order to prevent the possibility of accident, that a cord 

 should be fastened to the belt and then passed round the chimney, but 

 the ladder-irons, when driven about six inches into the brickwork, 



