Description of a new Anemovieicr . 949 



A wtll-sallinc; ship assumes -j of t.lie velocity of the wind. 

 The best-saihng ship 0*4 of the wind's velocity. 



The above formulas applied to the caladation (fa ship's way. 



Thus the wind 30, and the distance 70 miles, then the 

 numbiT of hours requisite lo traverse that distance will be 

 3-8 for 30x0-4= lt2 and l2)/0 = 5-S hours. 



Again 0"4 VV. being 12, and the hours, 5*8, being given, 

 the distance 70 miles, we have 5*8 x 12 = 69*6. by the se- 

 cond formula. 



And lastly, the nmnbcr of hours = 5*8, and space iu 

 miles = 70 being given, we have 0*4 of the velocity of the 

 wind = ^'V =12; and dividing this by 0-4 we bave the 

 rale per hour of its course in the lower atmosphere. 



'Explanation of the 'Drawing. (Plate IX.) 

 Fig. 1. The anemometer, with a vane or weather-cock 

 placed on the top, to show the direction of the lighter 

 winds, wliich could not be known by the anemometer, ou 

 account of the weight of the necessarv appendages an- 

 nexed to it. This is raised of a sufficient height above the 

 building, supported by a vertical axis or pole; the lower 

 end of it passes through the roof and cieling into an apart- 

 ment below. 



Fig. 2. Thelower part of the pole or vertical axis A A. fig, 1. 

 more enlarged, to give a better view of the necessary ap- 

 pendages. This pole is made of a slender spar, such as are 

 made use of for stro^ig setting poles for lighters, and han- 

 dles for boat-hooks, as not being affected by lightnings, 

 which iron too often is, and the cause of the destruction of 

 buildings and many lives. To this })ole is fastened a frame 

 of light wood by screws, in which the weights are con- 

 IJned, one on the top of another, iu grooves, in such a 

 manner as lo work up and down with the greatest faci- 

 lity. The weights are connected together by cords, and 

 maiked I, 2, 3, 4, &c.; the space bitwecn each, when 

 drawn up by the force of the wind, is ab(»ul one inch, as 

 may be seen by the drawing, and each weighs one pound 

 avoirdupois. To the top weight is fastened a line, and pass- 

 ing along the pole to the top, and over a brass pulley fixed 



at 



