Processes in the Useful Arts. 167 



the use for which it is designed. It is of course important to procure that 

 which is free from grit ; and it can be purified in a good degree by mix- 

 ing the powder with oil, and diluting it after it has stood a few minutes. 

 The heavier particles will form a sediment to be rejected. It is used on all 

 kinds of machinery where it is necessary to apply any unctuous substance 

 to diminish friction ; and it is said to be an excellent substitute for the 

 usual compositions applied to carriage- wheels. 



Some idea of the value of soapstone, in this use of it, may be formed 

 from the following fact, communicated by D. Moody, Esq. the superinten- 

 dant of the tar- works on the Mill-dam, near Boston : — Connected with the 

 rolling-machine of that establishment there is a horizontal balance-wheel 

 weighing fourteen tons, which runs on a step of five inches diameter, and 

 makes from seventy-five to a hundred and twenty-five revolutions in a mi- 

 nute. About a hundred tons of iron are rolled in this machine in a month ; 

 yet the wheel has sometimes been used from three to five weeks without 

 inconvenience, before the soapstone has been renewed. The superinten- 

 dent thinks, however, that it ought to be more frequently applied. 



This use of soapstone was discovered at Lowell by an accident, the cir- 

 cumstances of which it is not necessary now to repeat. It is sufficient to 

 say, that it is regarded by those who have used it as an invaluable disco- 

 very. I have been assured that it has never been known to fail of pro- 

 ducing the desired result, when applied to machinery which has begun to 

 be heated, even in those cases where nothing else could be found which 

 would answer the result. — Prof. Sillimans Journal of Science, No. xxvii. 

 p. 192. 



7« Anemoscope for ascertaining the Direction of Slight Winds. 

 By Mr B. M. Foster. 



This instrument consists of an octangular box, Plate II. Fig. 13, with a 

 circular opening in each of the sides. Within the box pieces of blotting- 

 paper are fastened which cover the openings. On the top of the box is a 

 tin tube or socket having a cork, with a ring by which it may be suspend- 

 ed in the air from a tree. If preferred, the cork may be taken out, and 

 the box may be placed in an inverted position on a pole., the upper end of 

 which goes into the tin tube. 



The method of using this instrument is to wet equally all the portions 

 of blotting-paper which appear through the holes, and then place the in- 

 strument in its proper position. When it has been exposed a short time 

 to the air, we must observe which portion of blotting-paper has dried most. 

 " Thin slabs of slate or of stone, which easily give out moisture," says Mr 

 Forster, 4f would be far preferable to using blotting-paper. This instru- 

 ment is founded on the principle by which I have understood sailors as- 

 certain the course of the air in a calm, which is, by wetting a finger, and 

 holding it up in the air ; then, by feeling which part becomes by evapora- 

 tion cool, they judge from whence the current of air flows. It is obvious 

 that when the sun shines erroneous conclusions may be made without due 

 attention." — London Journal of Arts* 



