BAIRD ^TATLOCK (LONDON) LTD. 



The^Hygrodeik. 



6135-6137 



6138 



The Hygrodeik is an improved form of the Mason Hygrometer, consisting of two thermometers (wet and dry 

 bulb) , mounted upon the outer edge of a chart plotted from standard wet and dry bulb tables. 



The Mason Hygrometer, while invariably recognised as the most accurate and satisfactory of the many forms 

 of Hygrometers in use, has never enjoyed the popularity which its merits deserve, owing to the annoying necessity 

 of reference to complicated tables for determining the Relative Humidity and Dew Point corresponding to the 

 ditii ronce in degrees between the wet and dry bulb Thermometers at different temperatures. 



The Hygrodeik charts, while complicated in appearance is simplicity itself, and obviates entirely the use 

 of tables for temperatures between 20 and 180 F. 



DIRECTIONS FOR READING THE HYGRODEIK. 



To find the Relative Humidity. 



Swing the index hand to the left of the chart, and adjust the sliding pointer to that degree of the wet bulb 

 thermometer scale at which the mercury stands. Then swing the index hand to the right until the sliding pointer 

 ersects the curved line which extends downward to the left from the degree of the dry bulb Thermometer scale 

 dicated by the top of the mercury column in the dry bulb tube. At this intersection the index hand will point 

 > the Relative Humidity on the scale at bottom of Chart. For example (see illustration), should the temperature 

 dicated by the wet bulb Thermometer be 60 and that of the dry bulb 70, the index hand will indicate humidity 

 "" when the pointer rests on the intersecting lines of 60 and 70. 



To find the Dew Point and absolute amount of Grains. 



Observe the intersection as above, and follow the curved line (passing through it, which runs from the top 

 downward to the right) to the point of contact with the dry bulb scale. The degree (53) at this point on that 

 (scale is the dew point required. The figure at the upper end of this line will give the absolute amount of water 

 I in grains (4.5 grains) per cubic foot of air. 



6135 s Hygrodeik, mounted on japanned iron frame, with base for standing . . . . each 



6136 s Hygrodeik, mounted on polished brass frame, with base for standing . . . . ,, 



6137 s Hygrodeik, designed to hang on wall ; strong hanger at top and in place of base, made 

 with brass cistern, mounted on polished brass, or brass nickelled frame . . each 



High Range Hygrodeik. The above hygrodeiks can be supplied with range 20 to 120 

 or So to 180 F. 

 6138 s The Pagoscope. A Frost Predictor 



A device for foretelling, early in the evening, whether there is or is not to be a frost during the following 



might, has been devised by a French meteorologist. It accomplishes its purpose by ascertaining whether or not 



the dew point, or point where the deposition of moisture from the atmosphere begins, is near, together with a 



sufficiently low temperature to insure that the moisture shall be deposited in a solid form. The familiar device 



[pf a Wet Bulb Thermometer is employed, the rapid evaporation of water from the moistened bulb lowering the 



temperature, and the more so as the air is drier and farther removed from the dew point. An ingenious mechanical 



[contrivance obviates the necessity of the usual mathematical calculations. This new instrument is, as may be 



extremely simple and of real practical interest for fruit growers, gardeners, and farmers in general. 



1 



2 



200 



100 



MCAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS- 



1121 



