26 



L. CASELLA'S CATALOGUE 



FIG. 78. 



of the large dial the low velocity of fifty feet per minute may be measured, 

 and by the smaller ones continuous registration is extended up to 10,000,000 

 feet, or 1893 miles, being practically beyond what the most extended 

 observations can require, whilst jewelling in the most sensitive parts, 

 ensures the utmost delicacy of action, FOEMING ALSO AN ADMIBABLE POCKET 



ANEMOMETEB FOE TEAVELLING, (fig. 75) p. 25 . . 440 



76. Air Meterj as above, with large dial to 100, and only one smaller dial to 



1000 . 3 10 



77. 'Anemometer (KOBINSON'S), plain, with four index wheels, registering successively 



100, 1000, 10,000, and 100,000 revolutions. In this arrangement the cups 

 travel at the rate of one-third the wind's velocity, and each revolution 

 represents 3.14 feet; thus, 3.14x3=9.42 feet, being the distance travelled 

 by the wind for each revolution. This, multiplied by the number of 

 revolutions indicated on the dial, shows the distance the wind has travelled 

 between one observation and another. The dials are read from right to left, 

 and the amount indicated at the last observation is to be deducted from 

 that shown on the dials at the time of the current observation 330 



78. ANEMOMETEB (EOBINSON'S IMPEOVED), for registering the velocity of the wind 



in miles and tenths, up to 505 miles, and described by Sir Henry James, 

 K.E., F.B.S., in his 'Instructions for taking Meteorological Observations' 

 (fe.78) . . . . . . 440 



