2(i6 farmers' and mechanics' journal. 



to others, and to himself, that respect which he ought, and " wh© 

 does as he would be done by," — then by all means give them learn- 

 ing. — The book in question will not make a man a Carpenter, or 

 a Philosopher, by merely buying it. It should be studied, and 

 studied attentively, and the person who has done that, will find 

 himself well paid for the trouble, and well prepared to proceed to 

 the higher and more important study of Architecture — a science, 

 as grand, as noble, as interesting, and, in this country, as little un- 

 derstood as any there is. 



OF SCA.RFING, &c. 



Taken [with a few omissions) from TredgoliTs Elemenfarij Principles of 



Carpentry. 



The joints having to support whatever strain^ the pieces joined 

 are exposed to, should be formed in such a m;i!iiui- that the bear- 

 rng,parts may have the greatest possible quantity of surface ; pro- 

 vided (hat surface be made of the l)est form for resi^-ting (lie strain^. 



For, should that part of the joint which receives the strain be 

 narrow and thin, it will of course either indent itself into the pieces 

 to which it is joined, or become crippled by the strain ; and which- 

 ever of these happens, a change must be produced in the form of 

 the framing. 



The etFect of (he shrinkage and expansion of timber should be 

 considered in the construction of joints. On account of the shrink- 

 age of timber, dovetail joints should never be used in carpentry, as 

 the smallest degree of shrinking allows the joint to draw out of its 

 place ; and, consecpjently. it loses all its efiect in holding the parts 

 in their proper si(uation. Dovetail joints can only be used with 

 success, when (he shrinkage of par(s counteract each other ; a case 

 which seldom happens in carpentry, but is common in joinery and 

 cabinet-making. 



Joints should also be formed so that the contraction or expan- 

 sion may not have a tendency to split .any part of the framing. 

 The force of contraction or expansion is capable of producing as- 

 tonishing effects where the pieces are confined, and may be some- 

 times observed in framing that has been wedged too tightly to- 

 ge(her in improper directions. The powerful effect of expanding 

 timber is well known to quarry-men, as they sometimes employ its 

 force to break up large stones. 



In forming joints, the object to be attained should always be 

 kept in view, as that which is excellent for one purpose may be 

 the worst possible for another. 



Of lengthening pieces of Timber, that are to resist strains in the 

 direction of their length. 



The simplest and perhaps the bes( n.ethod of lengthening a 

 beam is to abut the ends toge(ber. aiid p-rice a piece on each side ; 

 these, wken firmly bolted together, form a strong and simple con- 



