578 SEC. 14. METEOROLOGY. 



2834a. Anemometer, constructed by P. Schultze (Dorpat). 



Prof. A. von Getting en (Dor pat). 



After 50 revolutions of the Kobinson's cups an electrical contact is made, 

 but only for a small fraction of a second, because after the movement of the 

 differential wheel the electrical communication is broken, but at the same 

 time prepared for the next opera^on. 



2835. Anemometer (statical), in case. 



Dr. G. Recknagels, Kaisers lantern (Physical Collection of 



the Royal School of Industry). 



The indications of the instrument are proportional to the pressure of the 

 wind. The small size of the instrument, and the ease with which its indica- 

 tions may be read off, make it specially advantageous for investigating 

 ventilation. The velocities of the first revolution are marked on the outer 

 cale ; otherwise the constants are . given with the apparatus. A small 

 weight is added by way of a check ; it balances the spring suspended at a 

 mark of the hand. 



2835a. Two Anemometers. Dnrton. 



2S35b. Hewlett's Anemometer. Elliott Brothers. 



Consists of a copper sphere of such a diameter that the pressure of the 

 wind on its hemisphere shall be equal to the whole or any required portion 

 of a square foot ; the .sphere is mounted on a vertical rod that is suspended 

 on knife edges like a balance, and registers the force and direction of the 

 wind on a slate slab or on printed forms placed in the instrument for recording 

 daily observations. 



2836. Improved Anemometer of Combe. 



Herm. Recke, Freiberg, Saxony. 



All axle bearings in these anemometers are of stone. The setting and 

 suspending is accomplished by pulling at one and the same knob. To facilitate 

 the readings, dials with hands are provided. The fans are of trapezoidal shape 

 and reach nearly down to the axle ; they are of mica and capable of being 

 proved, in order to allow of the finding of the most sensitive position. 



2836a. Improved Anemometer of Combe. 



Herm. Recke, Freiberg, Saxony. 



In the preceding the axle of the fans remains unchanged during suspension 

 inasmuch as only the dial work is moved ; in this the axle is lifted parallel 

 to itself. 



2837. Pendulum Anemometer in a drawing, with explana- 

 tion. Professor Prestel, Emden. 



2838. Tangent Scale, for determining the mean direction of 

 the wind. Professor Prestel, Emden. 



2839. Balance Anemometer, constructed by Mr. Francis 

 Ronalds at the Kew Observatory, in 1843, for the purpose of 

 measuring the force of the wind. 



Kew Committee of the Royal Society, Kew Observatory. 



It consists of a light board, 1 foot square, fixed transversely to a cross of 

 wood, suspended by a brass axis passing through its centre, and turning in 



