250 Description of a new Anemometer. 



at the bottom of the square tube, under the sliding rod B, 

 fig. 3. as far as {a), and there fastened : in this sliding rod 

 a groove or channel is cut underneath, to receive the line, 

 so as not to impede its passage over the brass roUers^y. 

 The line is composed of a number of common sewmg 

 threarls, laid in different directions, well waxed, and in- 

 closed in a cotton case, to prevent as much as possible its 

 extension or contraction by the changes of the atmosphere. 



Fig. 3. The wooden pipe or tube two inches square, 

 fastened on the top of the pole ^. fig. 1. open on the side, 

 to show the manner that the sliding rod B passes over the 

 brass roUers/yy, when the wind is sufficiently strong to 

 lift up one pound by its force on the square surface pre- 

 sented to it, as (/;) and (c), fig. 4. 



Fig. 4. The wooden pipe or tube, in which are inclosed 

 the sliding rod, rollers, and line, from the effects of the 

 weather. 



Fis;- 5. The wooden frame, made of light wood, one foot 

 square, covered over with very thin sheet brass, strongly 

 painted, and varnished with copal. This frame is fastened 

 to the sliding rod B.Wig. 3. by means of a mortice, Sec. 



Fio" 6. An enlarged view of the scale and index, which 

 iTjaiks tlie greatest force-of the wind during the absence of 

 the observer, which is attached to the frame confining the 

 weights, as gh. fig. 2.; and beino; connected with the 

 hand fastened on the top weight {d. fig. 2.) raises the small 

 weight (p) ; and -this being counterpoised by another of 

 equal weight, by means of a line passing over a small pulley, 

 as represented bv this fig. and also g. fig. 2, occasions the 

 .small weight, with its index, to stop at the number of 

 pounds raised by the force of the wind, though they should 

 fall down into their proper places on the wind's abating. 



The bottom of the vertical axis or pole F. fig. 2, is 

 sheathed with a steel point, and a socket, which rest on a 

 wooden stand or frame, as at d. fig. 1, so as to turn with 

 case, and avoid as much as possible any friction. 



1 liave also to remark, that in order to render this simple 

 machine more complete, atrd answer the purpose of an 

 anemoscopcj as well as an anemometer, it is only neces- 

 sary to apply t') that part of the pole or axis, which is in 

 the apartment, an index, and attach to the cieling a thin 

 deal board, or a sheet of pastebcurd, with the points of the 

 ponipa^s marked thereon. 



A Table 



