294 PROFESSOR C. PIAZZI SMYTH ON 



graved steel-plate frontispiece, are devoted to the said cloud, its appearance and meaning. 

 This being presently deduced to be, an excessively intense example of the " Leste"; or a 

 hot wind which occasionally blows upon the higher hill tops in Madeira, straight out from 

 the Saharan Desert of Africa. But that is a sort of furnace of reflection for Solar heat, 

 and wherein the Palermitan Astronomers, observing the out-bursting of hydrogen red 

 prominences in the Sun, had already learned in 1872, to trace a connection between them, 

 and the out-rushes of hot Sirocco wind and dust clouds from the same African desert. 



But in the little book above mentioned, I also attempted to trace the symptoms and 

 opportunities of the cloud of June 26, being one of those remarkable cases which M. 

 Gaston Plante (the distinguished inventor of secondary batteries, which, under the new 

 name of accumulators, are now rendering the use of electricity in domestic electric lighting 

 almost as easy and manageable as coal-gas from any Gas Company's large gasometers), 

 — M. Gaston Plante I repeat, has endeavoured to demonstrate, respecting exchange 

 of internal, and as it were innate electricity between the earth and the Sun. 



Having communicated therefore to that gentleman, the resurgence of the important 

 date of June 26, and several following weeks in 1881, as a period of exaltation of heat 

 external to the earth striking upon it, according to the testimony of the Edinburgh Earth 

 Thermometers, — I was honoured by receiving the following letter from him : — 



Paris, 12 Rue des Vosges, 21 Mai 1888. 

 {Translated). 



I have read with a lively interest that which you have written to me of the elevation of the 



temperature of our glohe on the 26th of June 1881. I recall to myself still the excessive heat, altogether ex- 

 ceptional which we had in Paris, at that epoch. 



I find, on consulting my notes of that year, 1881, that the weather was very hot, and very heavy (lourd) 

 and by consequence very electric, from the 25th to the 28th of June. Then on the 3rd, 4th, and especially 

 the 5th of July, also on the 13, 14, 15, 16, 17, 18, and 19 July. The 19th of July in particular, when there 

 occurred, according to the papers of that date, 38° Cent, in Paris ; a temperature which I believe was never 

 known to have been experienced before. 



It is then probable, that there was at that epoch, as you have thought, a sort of irruption of a flux of 

 electricity on our globe ; or a freeing (degagement) of electricity in abundance, coming forth (emananl) from 



the globe itself under the influence of the Solar Electricity 



(Signed) Gaston PlantI 



After this, the least that I could do, in utilising the original observations further, 

 seemed to be, to recompute for the three most important thermometers all their simple 

 readings concerned in the above phenomenal summer and autumn ; or for the three whole 

 years 1880, 81 and 82. 



Representing for that period of time, their annual means (our only method at present 

 of eliminating the seasons or ordinary summer and winter divergences) — in three different 

 modes, viz., by collecting strictly annual means first for every Quarter, then every Month, 

 and finally every "Week, — though the latter is probably a needless refinement. 



The numbers however arrived at in each case, have been given without reserve, in 

 the Supplement of 8 pages appended to this paper ; as well as exhibited in three Plates, 

 appropriately drawn for their reproduction by Photo-lithography. And while they con- 



