602 SEC. 14. - METEOROLOGY. 



2937. Shortrede's Barometric Slide Rule, as arranged by 

 Major-General A. De Lisle, R.E., for barometric readings and 

 boiling points. Elliott Brothers. 



Thebarometric scale is calculated from Bailey's formula. The range ex- 

 tends to about 15,000 feet of altitude, occupying the three faces of the slides. 

 The back has logarithmic lines for computing the corrections, scales of which 

 are given on the edges. The method of using the lines is given on the face 

 of the rule. The corrections are : 1st, for temperature of mercury ; 2nd, for 

 temperature of air ; and, 3rd, for latitude. Aneroids only require the two last. 

 This rule was invented by the late Major-General Shortrede, formerly of the 

 Great Trigonometrical Survey in India. 



The logarithmic slide solves the following equations : 

 T = aZ> . a . = ^ ; ' 



O C do 



c a 2 



2938. Thermometer Screen for meteorological stations of the 

 2nd order. In use at the stations of the Norway Meteorological 

 Institute. Professor H. Mohn, Christiania. 



Made of plate iron. To be mounted outside a window and kept in shade. 

 The screen contains one psychrometer (dry and wet bulb), one minimum 

 thermometer (both instruments made by R. Grave in Stockholm), and one 

 hair-hygrometer (made by Herman and Pfister in Bern). The screen is 

 constructed after the designs of Professor H. Mohn. 



2939. Thermometer Screen for one single thermometer for 

 obtaining the temperature of the air. In use at stations belonging 

 to the Norway Meteorological Institute. 



Professor H. Mohn, Christiania. 



Made of plate iron. To be mounted outside a window or on a wall, and kept 

 in shade. With thermometer, made by R. Grave, in Stockholm. Screen 

 constructed after the design of Professor H. Mohn. 



2940. Thermometer Screen for one minimum thermometer. 

 In use at stations belonging to the Norway Meteorological Insti- 

 tute. Professor H. Mohn, Christiania. 



Made of plate iron, with double walls. Suspended on a cylindrical rod 

 intended to pass through the window-frame. The rod has a handle inside, so 

 that the screen with the thermometer can be turned for " setting " in the same 

 way as a thermograph. The double walls prevent the rising of the ther- 

 mometer, even in direct sunshine, to more than a few degreqe above the 

 temperature of the air. The minimum thermometer is made by R. Grave, in 

 Stockholm. The screen is executed after designs of Prof. H. Mohn. 



2941. Stevenson's Box for Thermometers. 



Scottish Meteorological Society. 



The box is louvre-boarded, and painted white inside and outside, and 

 screwed to four stout posts, also painted white, firmly fixed in the ground. 

 The posts must be of such a length that when the thermometers are hung in 

 position the bulbs of the minimum thermometer, and of the dry and wet bulb 

 thermometers, will be exactly at the same height of 4 feet above the ground, 

 the maximum thermometer being hung immediately above the minimum 



