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would appear to attain its maximum on that side of the sun which is turned 
away from Venus, and to have its minimum in the neighbourhood of this 
planet.” 
In reply to the question, Does not Jupiter appear to exert any influence ? 
as, although its distance is much greater than that of Venus, yet its mass is 
very great, it is shown that the influence of Jupiter is really great, although 
not apparently predominating. 
Not only have we these effects in longitude, hut it would appear that 
spots are nearest to the solar equator when the heliographical latitude of 
Venus is 0°, and are most distant from the solar equator when this planet 
attains its greatest heliographical latitude. 
The concluding remarks of the authors are as follows : — 
“ The following question may occur to our readers, How is it possible that 
a planet so far from the sun as Venus or Jupiter can cause mechanical 
changes so vast as those which sun-spots exhibit P We would reply in the 
following terms to this objection : 
“We do not, of course, imagine that we have as yet determined the 
nature of the influence exerted by these planets on the sun ; but we would, 
nevertheless, refer to an opinion expressed by Professor Tait, ‘that the pro- 
perties of a body, especially those with respect to heat and light, may be 
influenced by the neighbourhood of a large body.’ Now, an influence of 
this kind would naturally be most powerful upon a body such as the sun, 
which possesses a very high temperature, just as a poker thrust into a hot 
furnace will create a greater disturbance of the heat than if thrust into a 
chamber very little hotter than itself. In the next place, it is not to be 
inferred that the mechanical equivalent of the energy exhibited in sun-spots 
is derived from the influencing planet any more than it is to be inferred that 
the energy of a cannon-ball is derived from the force with which the trigger 
is pulled.* 
“ The molecular state of the sun, just as that of the cannon or of fulmi- 
nating powder, may be extremely sensitive to impressions from without ; 
indeed we have independent grounds for supposing that such is the case. 
We may infer from certain experiments, especially those of Cagniard de 
Latour, that at a very high temperature and under a very great pressure 
the latent heat of vaporisation is very small, so that a comparatively small 
increment of heat will cause a considerable mass of liquid to assume the 
gaseous form, and vice versa. W e may thus very well suppose that an 
extremely small withdrawal of heat from the sun might cause a copious 
condensation ; and this change of molecular state would, of course, by means 
of altered reflection, &c., alter to a "considerable extent the distribution over 
the various particles of the sun’s surface of an enormous quantity of heat, 
and great mechanical changes might very easily result. 
“ Again, although we cannot suppose our earth to be nearly so sensitive 
as the sun, yet the question may be entertained, Does the moon exert an 
influence of this kind upon the earth ?” 
It is not a little curious that since the authors’ preliminary research into 
* It is, however, a possible enquiry whether these phenomena do net imply 
a certain loss of motion in the influencing planets. 
