58 COMMODIOUS HOUSES WITH EARTHEN WALLS. **'* 



ferent methods of accomplishing this object. Figure 3, M, 

 is that which is used in the model left at the Society's Re- 

 pository. A small key or screw S is pot down through a hole 

 in the lid of the lock, and is received into a hole lapped with 

 a screw in the click ; by turning the screw it lifts the click 

 out of the teeth of the rack; so that the moving frames fg 

 can be opened apart from each other, till they lie flat upon 

 the frame A B. The iron cross m is then put between the 

 two rodsfg, the screws S of the two locks are to be with- 

 drawn from the locks, and the trap is set for use. If an of- 

 fender should place his foot within the square of the frame, 

 he would tread down the cress m, and having thus removed 

 the obstruction, the two frames efeg are closed together by 

 the springs p p, so that the bars/or enclose his leg, and the 

 clicks in the locks prevent the bars being opened without 

 the screws S. In some of the machines which Mr. Salmon 

 has made since the model was deposited with the Society, 

 the locks are made like rigure 2, L, where a common key is 

 to be introduced, and, when turned round, catches the tail of 

 the click ; it may have wards to prevent the using of a false 

 key, though no wards are shown in the plate. 



Screw for fix- Part of the screw D for securing the trap from being car- 



in 8 the y gound. ried awa y ky depredators, is shown on a larger scale at N, in 



order that the peculiar form of its threads may be better 



seen, which fix it firmly in the earth. Such screws would 



be very serviceable in fastening horses at grass, &c. 



XII. 



Method of constructing commodious Houses with Earthen 

 Walls. By Mr, Robert Salmon, of JVoburn*. 



Dear Sir, 



Building JTjLaYING for some years past practised at this place the 



art of pise, or constructing walls with earth ; and having in 



houi.es with 

 earth 



* Trans, of the Soc. Arts, vol.' XXVII, p. 185. Twenty guineas were 

 voted to Mr. Salmon for this coinniunicalion. 



consequence 



