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la ship building the great mistake heretofore experienced has arisen from the commixture 

 of more perishable or decayed timber with that which was sound and durable. This is 

 exemplified by the condition of some of our old sliips when broken up. In liouse 

 building error?, though not so fatal to life and property, are often c().iiniiti(d : witness, lor 

 instance, the warped and kimbo positions now presented by country dwellings that were once 

 elegant and symmetrical. 



The evil does not end here. Of the thousand houses now being erected in the city of 

 New York and its suburbs, not one, I will venture to assort, has the beams on which the 

 floors are being laid well seasoned ; the consequence is, after the buildings are finished, 

 they shrink from the base boards, and leave openings for the intrusion not only of currents 

 of cold air, but for mice and various creeping things. 



The use of unsound timber may, and no doubt does frequently, arise from the sheer 

 ignorance of the workman ; sometimes, however, it may be ascribed to design, in his selecting 

 that which is more easily Avrought in preference to durable quality. 



Where the disposition exists, a slight attention to the condition of timber before use would 

 in many cases prevent serious loss and evil. It is of the first importance both to our 

 government and to many individuals concerned in its use, that disinterested inspectors should 

 have the selection of all timber required in ship building, and the use of any other 

 should be strictly prohibited. With the practice of such precautions a great improvement in 

 ship and all other building could not fail to follow. 



But to guard effectually against the decay of timber something more than a close inspection 

 will be found necessary, and to this science points with imcrring certainty. 



It consists in filling the sap vessels of timber with some antiseptic substance or substances 

 which shall fix the caseous and soluble portions permanently, or, by imiting with them, 

 arrest their putrifactive tendency. 



Substances of this character are numerous ; but in their selection a strict regard should 

 be had to economy. Mr. Kyan first introduced the practice of preserving timber by filling 

 its pores with corrosive sublimate or oxymuriate of mercury ; hence the term of kyanizing. 

 This process has been abandoned and cheaper ones substituted for it. Among them may be 

 included all the sulphates and sulphate-triple salts, which contain an excess of acid; dilute 

 sulphurous and sulphuric acid, concentrated vegetable acds, some of the volatile oils, pitch, 

 uurectified creosote, most of the metallic and some of the alkaline and earthy salts. In fact 

 any substance that will act upon the caseous or albuminous j)ortions of timber and change 



