54 PLEASANT WA KS IN SCIENCE. 



coal, such details as could only he detected by close scrutiny, 

 can affect the general quality and effects of the heat trans- 

 mitted by the coal, as part of a large fire, to the further side 

 of a large room. 



Lastly, I would urge this general argument against a 

 theory which seems to me to have even less to recommend 

 it to acceptance than the faith in astrology.* If it requires, 



* It must be understood that this remark relates only to the theory 

 that by close scrutiny of the sun a power of predicting weather pecu- 

 liarities can be obtained, not to the theory that there may be a cyclic 

 association between sun-spots and the weather. If this association 

 exists, yet no scrutiny of the sun can tell us more than we already know, 

 and it will scarcely be pretended that new solar observatories could 

 give us any better general idea of the progress of the great sun-spot 

 period than we obtain from observatories already in existence, or, 

 indeed, might obtain from the observations of a single amateur tele- 

 scopist 



I think it quite possible that, from the systematic study of terrestrial 

 relations, the existence of a cyclic association between the great spot 

 period and terrestrial phenomena may be demonstrated, instead of being 

 merely surmised, as at present By the way, it may be worth noting 

 that a prediction relative to the coming winter [that of 1877-78] has 

 been made on the faith of such association by Professor Piazzi Smyth. 

 It runs as follows : 



" Having recently computed the remaining observations of our 

 earth-thermometers here, and prepared a new projection of all the ob- 

 servations from their beginning in 1837 to their calamitous close last 

 year [1876] results generally confirmatory of those arrived at in 1870 

 have been obtained, but with more pointed and immediate bearing on 

 the weather now before us. 



" The chief features undoubtedly deducible for the past thirty-nine 

 years, after eliminating the more seasonal effects of ordinary summer 

 and winter, are : 



" i. Between 1837 and 1876 three great heat-waves, from without, 

 struck this part of the earth, viz., the first in 1846*5, the second in 

 1858 X), and the third in i868'7. And unless some very complete altera- 

 tion in the weather is to take place, the next such visitation may be 

 looked for in 1879*5, within limits of half a year each way. 



"2. The next feature in magnitude and certainty is that the periods 

 of minimum temperature, or cold, are not either in, or anywhere near, 

 the middle time between the crests of those three chronologically 

 identified heat-waves, but are comparatively close up to them on eilhti 



