VOL. LXVIII.] PHILOSOPHICAL TRANSACTIONS. 449 



vided it be not too dry to be spread properly on the laths. If the flooring boards 

 are required to be laid very soon, a 4th or a 5th part of quick* lime in powder, 

 very well mixed with this rough plaster just before it is used, will cause it to dry 

 very fast 



§ 10. When the rough plaster-work between the joists has got thoroughly dry, 

 it ought to be observed whether there be any small cracks in it, particularly next 

 to the joists. If there are any, they ought to be washed over with a brush, wet 

 with mortar-wash, which will effectually close them; but there will never be any 

 cracks at all, if the chopped hay and the quick lime be properly used. 



^11. The mortar-wasli made use of is merely this. About 1 measures of 

 quick lime, and 1 measure of common sand, should be put into a pail, and 

 should be well stirred up with water, till the water grows very thick, so as to be 

 almost of the consistency of a thin jelly. This wash, when used, will get dry 

 in a few minutes. 



§ 12. Before the flooring boards are laid, a small quantity of very dry common 

 sand should be strewed over the rough plaster-work, but not over the tops of 

 the joists. The sand should be struck smooth with a hollow rule, which ought 

 to be about the length of the distance from joist to joist, and of about -f of an 

 inch curvature; which rule, passing over the sand, in the same direction with the 

 joists, will cause the sand to lie rather rounding in the middle of the interval be- 

 tween each pair of joists. The flooring boards may then be laid and fastened 

 down in the usual manner; but very particular attention must be paid to the 

 rough plaster- work and to the sand being most perfectly dry before the boards 

 are laid, for fear of the dry-rot; of which however there is no kind of danger, 

 when this precaution is observed. 



^ 13. The method of under-flooring Lord M. has also applied, with the ut- 

 most success, to a wooden stair-case. It is made to follow the shape of the steps, 

 but no sand is laid on the rough plaster-work in this case. 



^ 14. The method of extra-lathing may be applied to cieling joists, to sloping 

 roofs, and to wooden partitions. It is simply this: as the laths are about to be 

 nailed on, some of the above mentioned rough plaster ought to be spread be- 

 tween these latVis and the joists, or other timbers, against which the laths are to 

 be nailed. The laths ought to be nailed very close to each other. When either 

 of the ends of any of the laths laps over other laths, it ought to be attended to 

 that these ends be bedded sound in some of the same kind of rough plaster. 



* Lord M. practised this method in an extensive work with great advantage. In 3 weeks this 

 rough plaster grows perfectly dry. The rough plaster, so made, may be applied at all times of the 

 year with the greatest success. The easiest method, by much, of reducing the quick lime to powder 

 is, by dropping a small quantity of water on the lime-stone, a little while before the powder is in- 

 tended to be used; the lime will still retain a very sufficient degree of heat. — Orig. 

 VOL. XIV. 3 M 



