Address of Sir William Thompson. 291 
profound secret and mystery of nature concerned in the pheno- 
 ‘menon of their tails. “Perhaps it is not too much to hope that 
future observation, borrowing every aid from rational specula- 
tion, grounded on the progress of physical science generally 
(especially those branches of it which relate to the ethereal or 
of avoidance.” “In no respect is the question as to the mate- 
riality of the tail more forcibly pressed on us for consideration 
Sun in perthelioin a manner of astraightand rigid rod, in defiance 
of the law of gravitation, nay, even of the received laws of motion. 
“The projection of this ray ... . t ! 
: single day, conveys an impression of the intensity of the 
ting to produce 
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as we conceive it, viz., possessing mertia—at all, it pe sid 
the dominion of forces incomparably more energetic — 
tation, and quite of a different nature.” ca : ; = 
l, : th of the admirable simplicity with which se 8 
beautifal “ sea-bird analogy,” as it has been called, can expiain 
all these phenomena. 
ing i ogic itions very 
pressing it that, under meteorological condl 
erent care e peer dead matter may have run together, 
