March 1, 1861.1 THE TECHNOLOGIST. 



THE SPECIFIC WEIGHT OF WOODS, ETC. 365 



China Silkworm. — This is smaller than the Cashmere worm, and 

 differently marked. From the time of hatching to the time of spinning, 

 during the rains, it took seventeen days. 



It is to he treated in the same way as the other. In Bengal during 

 the first stage, the China silkworms are fed on leaves, cut up into thin 

 strips hy means of a knife, and they are kept up to their first change of 

 skin, in shallow earthen pans (gumlahs). They are regularly fed four 

 times in the day and twice at night, and not touched till they change 

 their first skin, when whole leaves are placed upon them, and as soon as 

 they creep upon the leaves, they are removed to clean trays. The old 

 leaves and excrements are only changed at each moult. 



The eggs of the China worm adhere to the ohject on which they are 

 laid, and therefore the female moths after pairing must he placed on 

 sheets of paper a little distance from each other. The eggs of this worm 

 will hatch again in about eight or nine days after they are laid. In 

 Bengal, it gives about seven crops in the year. Temperature has great 

 influence in retarding or accelerating the period of its existence. Those 

 that hatched in June took seventeen days, and those that hatched in 

 November took fifty-one days to go through all their changes. 



The above is intended only to give some idea of rearing silkworms, 

 but those who wish to learn more about them can easily obtain a small 

 quantity of eggs, and observe the worms while going through their 

 various stages. 



Lucknow, Sept. 1863. 



ON A MEANS OF RENDERING OSTENSIBLE THE SPECIFIC 

 WEIGHT OF WOODS, &c. 



BT PROFESSOR J. ARNAUDON. 



When 'passing in review the different systems of classification of 

 woods,* I had previously taken the opportunity of considering th e 

 weight as the starting point of an artificial arrangement which pretty 

 well agrees with another one by which the woods are classified accord- 

 ing to the greater or less resistance they oppose to tools. In the 

 collections arranged according to their specific weights, the wood is gene- 

 rally presented so as to exhibit one form and one volume, the difference 

 of heaviness of these similar pieces indicating their corresponding 

 specific weight. It is obvious that, disposed in this manner in a museum, 

 nothing else than a label or inscription will indicate to the visitor the 

 relative heaviness of the wood ; but if, on the contrary, we give the same 



* See Technologist, vol. iii., p. 97. 



