94 . _ Mr. C. Tomlinson's Experimental Examination 



(microscopically watched) grows like fir or fern leaves, hoar frost, 

 or crystallizations. 



"As it tends to the opposite quarter, the lines or spikes— all 

 regular hard and crisp features — gradually vanish. Before and 

 in a continued southerly wind, the mixture sinks gradually down- 

 wards in the vial till it becomes shapeless like melted sugar. 



" Before or during the Continuance of a northerly wind (polar 

 current) the crystallizations are beautiful (if the mixture is cor^ 

 rect, the glass a fixture, and duly placed) . The least motion of 

 the liquid disturbs them. The glass should be wiped clean now 

 and then gently if exposed to rain or dust*. 



"While any hard or crisp features are visible below, above, or 

 at the top of the liquid (where they form for much north wind), 

 there is plus electricity in the air ; a mixture of polar current co- 

 existing in that locality with the opposite or southerly. When 

 nothing but soft, melting, sugary substance is seen, the atmo- 

 spheric current (feeble or strong, as it may be) is southerly f, 

 unmixed with, and uninfluenced by, the contrary windf. 



" By repeated trials with a delicate galvanometer, applied to 

 measure electrical tension in the air, I have proved these facts, 

 and now find them useful for aiding, with the barometer and 

 thermometer, in forecasting weather. 



"Temperature affects the mixture much, but not solely, as 

 many comparisons of winter with summer changes of tempera- 

 ture have fully demonstrated." 



- In the f Weather Book ' it is stated that [" clearness of the 

 liquid, with more or less perfect crystallizations, accompanies a 

 combination or a contest of the main currents by the west. And 

 very remarkable these differences are, — the results of these air 

 currents acting on each other from eastward, or entirely from an 

 opposite direction, the west" §. 



The composition of the storm-glass is said to be " camphor, 

 nitrate of potassium and sal-ammoniac, partly dissolved by 

 alcohol, with water and some air, in a hermetically sealed glass 



* In the ' Weather Book ' it is added, " once or twice in a year the mix- 

 ture should be disturbed by inverting and gently shaking the glass vial." 



t In the * Weather Book ' it is added, " with minus electricity." 



% " A confused appearance of the mixture with flaky spots or stars in 

 motion and less clearness of the liquid indicates south-east wind, perhaps 

 a gale." 



§ Several incidental passages in the 'Weather Book* confer a high 

 scientific value on the storm-glass. Thus at page 209 it is said that " ther- 

 mometers and camphor-glasses also contribute their indications " in predict- 

 ing local storms. And again, page 232, "camphor-glasses in proper posi- 

 tions and duly attended are most useful to a quick eye and skilled percep- 

 tion." . 



