i9"] METEOROLOGICAL INSTRUMENTS 207 



the calm the surface layer of cold air is extremely thin and that 

 there is a steep inverted gradient. When the wind arose the 

 sky overhead was clearer than I ever remember to have seen it, 

 the constellations brilliant, and the Milky Way like a bright 

 auroral streamer. 



The wind has continued all day, making it unpleasant out of 

 doors. I went for a walk over the land; it was dark, the rock 

 very black, very little snow lying; old footprints in the soft, 

 sandy soil were filled with snow, showing quite white on a black 

 ground. Have been digging away at food statistics. 



Simpson has just given us a discourse, in the ordinary lecture 

 series, on his instruments. Having already described these in- 

 struments, there is little to comment upon; he is excellently lucid 

 in his explanations. 



As an analogy to the attempt to make a scientific observation 

 when the condition under consideration is affected by the means 

 employed, he rather quaintly cited the impossibility of discover- 

 ing the length of trousers by bending over to see ! 



The following are the instruments described: 



The outside (bimetallic) Features 



thermograph. 

 The inside thermograph 



(alcohol) Alcohol in spiral, small lead 



pipe float vessel. 

 The electrically recording 



anemometer -. . . Cam device with contact on 



wheel; slowing arrange- 

 ment, inertia of wheel. 

 The Dynes anemometer .... Parabola on immersed float. 

 The recording wind vane .... Metallic pen. 



The magnetometer Horizontal force measured 



in two directions verti- 

 cal force in one timing 

 The high and low potential arrangement, 



apparatus of the balloon 



thermograph Spotting arrangement and 



difference, see ante. 



Simpson is admirable as a worker, admirable as a scientist, 

 and admirable as a lecturer. 



