3i8 PETER GUTHRIE TAIT 



My correspondent writes from Galway, to the following effect, on the 2nd of 

 the present month : 



"At the commencement of the present unprecedently long and severe storm the wind 

 blew from south-west and was very warm. After blowing for about two days it became, 

 without change of direction, exceedingly bitter and cold ; and the rain was, from time to time, 

 mixed with sleet and hail, and lightning was occasional. This special weather is common 

 for weeks together in March or early April. The air is (like what an east wind brings in 

 Edinburgh) cold, raw, dry, and in every way uncomfortable, especially to people accustomed 

 to the moist Atlantic winds. During these weeks a series of small clouds, whose shadows 

 would only cover a field of a few acres, seem to start at regular intervals from the peaks of 

 hills in Connemara and Mayo. They are all more or less charged with electricity. From 

 high ground, behind the city, I have at one time seen such a cloud break into lightning 

 over the spire of the Jesuits' church. At another, I have seen such a cloud pour down in a 

 thin line of fire, and fall into the bay in the shape of a small incandescent ball. On one 

 occasion I was walking with a friend, when I remarked, ' Let us turn and make a run for it. 

 We have walked unwittingly right underneath a little thundercloud.' I had scarcely spoken 

 when a something flashed on the stony ground at our very feet, a tremendous crash pealed over 

 our heads, and the smell of sulphur was unmistakable. I fancy that I have been struck with 

 these phenomena more than others, from the circumstance that they have always interfered 

 with my daily habits. My walks often extended to considerable distances and to very lonely 

 districts. Now these small local spurts of thunderstorms would hardly excite attention in the 

 middle of a town, all the less as the intervening weather is bright, though raw these spurts 

 coming on every three or four quarters of an hour. Neither would they excite much atten- 

 tion in the country, as, while such a little storm was going on in one's immediate neighbourhood, 

 you would see at no great distance every sign of fine weather. In fact they always seem to 

 me like the small change of a big storm." 



My correspondent, though a good observer and eloquent in description, is not 

 a scientific man 1 . But it is quite clear from what he says that a residence of a few 

 weeks in Galway, at the proper season, would enable a trained physicist to obtain, 

 with little trouble, the means of solving this extremely interesting question. He 

 would require to be furnished with an electrometer, a hygrometer, and a few other 

 simple pieces of apparatus, as well as with a light suit of plate armour, not of steel 

 but of the best conducting copper, to insure his personal safety. Thus armed he 

 might fearlessly invade the very nest or hatching-place of the phenomenon, on the 

 top of one of the Connemara hills. It is to be hoped that some of the rising genera- 

 tion of physicists may speedily make the attempt, in the spirit of the ancient chivalry, 

 but with the offensive and defensive weapons of modern science. 



Another possible source of the electricity of thunderstorms has been pointed out 

 by Sir W. Thomson. It is based on the experimental fact that the lower air is 

 usually charged with negative electricity. If ascending currents carry up this lower 

 air the electricity formerly spread in a thin stratum over a large surface may, by 

 convection, be brought into a very much less diffused state, and thus be raised to a 

 potential sufficient to enable it to give a spark. 



1 The correspondent was probably the late Professor D'Arcy Thompson, of Galway, 

 already referred to on p. 238. 



