1850.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



18» 



(2.) With close lathing, as in England, 'a lattis jointif.' 



(2) A Lattis Jointif. 



(3.) The third manner, and the one most usually adopted, because 

 it binds the joists together the most effectually, without loading 

 them unnecessarily, consists in lathing the underside of the joists 

 at distances of about 3^ inches from centre to centre. A species 

 of flat centering is then placed under them, and a coat of plaster 

 of about Ij to l| inch is laid over the laths so as to stop against 

 the boards on either side, and between them. The plaster is 

 brought up the sides of the joists, and worked so as to leave a 

 hollow channel. The ceiling itself is then applied below this coat, 

 called an 'auget.' 



(3) Aveo Augets, en Cannivaiuc. 



(4.)In the country, again, another manner is used, namely, the 

 joists are left apparent, and only the intermediate spaces are ceiled. 

 If the third manner could be adopted under the requisite conditions 

 of economy, it would be very desirable, for it unites the great 

 advantages of solidity and of impermeability to sound, in which 

 respect our newly-built houses leave so much to be desired. 



(4) A Solives Apparentes. 



Note. — The parts shaded with parallel lines represent the laths; the blank 

 parts a a represent the plaster; those marked b b represent the floor boards 

 or tiles, as the case may be. No. 1 counts for the value of 1 J times No. 2. 

 No. 2 constitutes the unity of price for common plastering — it is called 

 " leger." Thus, No. 1 is said to be " IJ leger," and paid for at that rate. 

 No. 3 counts for " 1 J leger." No. 4 counts also for " \\ leger." 



Now, the proprietors of the French quarries have lately made 

 arrangements by which the real plaster of, and from, Paris may be 

 obtained in London at prices below those of our English plaster. 

 Its use will, I am personally convinced, very soon supersede the 

 barbarous mixtures of lime and hair, and all such trumpery, we 

 have been forced to employ hitherto in its absence. A new apjili- 

 cation of any material is, however, always exposed to many rislcs 

 and failures ; from ignorance of its qualities, from unskilfulness 

 in the handling, and even from the prejudices of those employed 

 to execute the works. It may therefore be necessary to endeavour 

 to point out the conditions requisite to ensure the successful essay 

 of the one we are now considering. 



Firstly. It is not advisable in the commonest sorts of work to 

 allow more than two parts of sand to be mixed with one of plaster; 

 for better works, one and one should be used. Tlie setting coat 

 should be of pure plaster; my own opinion is that large quantities 

 of putty, or other preparation of the carbonate of lime, should 

 not be used, though there does not appear to be any objection to 

 the plaster being guaged with lime-water, which not only retards 

 the setting, but also diminishes the expansion. 



Secondly. My own experience with French workmen would lead 

 me to say that we must not expect to be able to maintain, with a 

 material which sets so rapidly as the plaster of Paris, surfaces so 

 mathematically true as we do obtain in the usual system followed 

 by our builders. In Paris, for several reasons, this exactness is 

 not required; the rooms are smaller, it is not the fashion to have 

 large unpannelled walls, or to use even, flat, tints. Small ine- 

 qualities of surface are not, under such circumstances, of so much 

 moment as they are to ourselves. Indeed we may form a tolerably 

 corect idea of the comparative slovenliness with which plasterers' 

 work is done there, from the fact that some of the workmen execute 

 both it and the masonry on which it is applied. In all the build- 

 ings in Paris I have visited, the plastering has been executed with 

 a carelessness which would disgust any London architect. The 

 angles are never square, or true; the upright faces hardly ever 

 " out of winding," or " plomb." Yet when our own more skilful 

 workmen have overcome their prejudices, and learnt the proper 

 use of this material, we have every reason to believe that they will 

 make as perfectly "true" work with it as with the others. At the 

 same time it attains in an incredibly sliort space of time a degree of 

 hardness we are totally unused to, and it is accompanied by the 

 immense advantage of only giving rise to about |ths of the evapo- 

 ration arising from ordinary plastering. A series of very carefnl 

 experiments has been made under the directions of Messrs. Piper, 

 which proves that the cost of ordinary works need not exceed 

 in any sensible proportion, if at all, those we call usually " render, 

 set :" that they are strictly the same as the render, float, and set ; 

 presenting a very superior article in every respect. Mr. Piper's 

 experiments go to show that the evaporation from the French 

 plaster is only about in the proportions just cited. In the Spicer 

 Street Model Lodging Houses, Messrs. Piper executed, during tlie 

 last week, a room which was begun and finished in thirty hours, 

 whilst a common lime and hair rendering coat would have required 

 a week at least ere it would have been fit to receive the floating 

 coat, and the whole operation would have required, properly 

 speaking, about a month. Mr. Beck, the architect, to whom all 

 praise is due for the merit of the buildings in the first place, and 

 for the sagacity which led him to try the new material, can vouch 

 for the quality of the work, and explain the means adopted to 

 obtain so very remarkable results. Subsecpient experiments must, 

 however, be made to ascertain the best mode of finishing superior 

 work upon plaster rendering, either by the use of Keene's Parian, 

 or Martin's cements; for it is my own perfect conviction that the 

 use of lime and hair will very shortly be abandoned. 



Thirdly. The French plaster must never be used in any position 

 where moisture is likely to affect it for any length of time. It is 

 very hygrometric, and soon decays if kept moist. The pi-evalence 

 of warm moisture, as for instance in cellars, also gives rise to the 

 formation of much saltpetre; its use in such places should then be 

 avoided. The same faculty of forming tlie saltpetre should, also, 

 make us very cautious as to the nature of the sand to be mixed 

 with the plaster. 



Fourthly. If the plaster be used as a mortar, for the purpose of 

 carrying up bricknogged partitions to be covered over immediately, 

 for which purpose, as said before, it would be invaluable, care must 

 ba taken to prevent the expansion of the plaster from affecting the 

 other work. It is usual, in France, to leave a small space between 

 the wall and the partitions, in carrying them up, which is subse- 

 quently filled-in by the plastering coat. The same observation 

 applies to floors with plaster pugging, and even to cornices with a 

 large body of that material. In the case of the latter, it is usual 

 to run the straight mouldings, and to execute the mitres, or returns, 

 subsequently. 'I'he projections of tlie cornices, by the way, are 

 carried out solid, with very little, if any bracketing. But we must 

 observe, that the French architects, very wisely, do not execute 

 such terribly heavy internal decorations as we do, and that conse- 

 quently their projections are less. 



In the above remarks, I have studiously avoided the questions 

 connected with the use of plaster in iron and pottery. They 

 would have swelled this paper, already too long, to limits far 

 beyond jour patience. It is my intention to request your conside- 

 ration of them upon some subsequent evening. In the mean time, 

 we may be allowed to congratulate ourselves upon the fact, that the 

 abolition of the excise upon bricks and tiles will enable us to make 

 much more complete experiments. 



I mav add that the parties who have made arrangements for the 

 sale of the French plaster in London, are Messrs. Piper of Bisbops- 

 gate-street, and Messrs. J. B. \Vhite and Sons, of Millbank-street. 

 The price at which it can now be sold, is about 2/. per ton at the 

 wharves. 



