1838.] 



eind Contraction of fVood. 



115 



so that I thought i hful eventually quite filled up the pores of the wood, 

 and made the rods, so far, impervious to moisture. As a further step 

 in the experiment I then varnished three of the rods, viz. Nos. 1, 4, and 

 6 ; the teak, mahogany, and fir ; laying on each three coats of spirit 

 varnish. It may be here observed that the fir rod No. 6 was now 

 doubly varnished, viz. varnished in the first experiment, then coated 

 with the foregoing mixture, and afterwards varnished again. On trying 

 the length of the rods after this process had been gone through, I 

 found that the whole of them had contracted considerably, but the ma- 

 hogany the most of all, notwithstanding it was so perfectly well 

 seasoned. The following table will shew the respective contractions^^ 

 from the original lengths. 



No. 1. Teak (coated with hot resinj wax, &c. and spirit var- 

 nish) contraction 0.0070 



2. Pal maram do. (wax, resin, &c. but not varnished) do. . . .0.0149 



3. Chittagong (do. do. ) do 0.0108 



4. Mahogany (do. and spirit varnish) do. . . .0.0256 



5. Fir (do. not varnished) do. ...0.0115 



6. Fir (do. and spirit varnish) do. .0.0083 



15. — This diminution in the length of the rods was not permanent" 

 The v/hole of them went on gradually increasing in length ffom the be- 

 ginning of March 1837, when the foregoing experiment was made, un- 

 til the 16th August following,, when it appeared that the Chittagong 

 rod, and the two fir rods, the softest woods, had fully recovered their 

 original lengths and a little more ; but the others had not. The fol- 

 lowing was the state of the rods on the foregoing date, viz. 16th August. 

 No. I. Teak minus, 0.0020 of an inch. 



2. Pal maram do. 0.0068 „ 



3. Chittagong plus .O.OOOS „ 



4. Mahogany minus 0.01/6 „ 



5. Fir plus .0.0006 



6. Fir do 0.0006 



16. — In November they had all recovered their original lengths, ex- 

 c jpt the mahogany, which, up to the present date, seems to have under- 

 gone a permanent contraction. The underoicntioned table will shew 

 their lengths as ascertained on several occasions in November and. 

 December 1837. 



