~~  e 
<a A 

ADDRESS. XXXIX 
noticed ; and gives the prompt and easy means of making the comparison; 
so easy, that probably before its epoch, 1850, is past, every one of tliose 
places will have been verified in the sky. Such an undertaking could have 
been effected only by such a power as ours, which could at once engage the 
services of such men as Baily, Herschel, Stratford and their fellow-labourers, 
and devote to the inferior part of the work an expenditure exceeding 20001, 
Jn fact, had we done nothing else, I say fearlessly that this work alone would 
have secured us an enduring claim on the gratitude of science. Let me here 
remark, that there are many other departments in which we could render 
most important service by the mere collection of the Constants that belong 
to them; as we have done in this case and in that of terrestrial magnetism. 
Constants are the framework of knowledge, the concentration of power; 
they belong peculiarly to our domain, and were marked out as such long 
since; but though unfortunately this work was not executed by that power- 
ful mind to whom we entrusted it, I hope the subject will not be forgotten, 
I might tell you of the theory of the tides, which Laplace might well style 
‘the most thorny of problems,” but of the greatest interest to a nation 
“ Whose march is o’er the mountain wave, 
Whose home is on the deep.” 
I might tell you of light thrown on it by observations obtained by our influ- 
ence, reduced at our expense, and unravelled by one worthy of going be- 
yond the steps of Newton and Bernouilli. To the same philosopher we owe 
the execution of another important task,—the determination of the plane which 
marks the level of the sea unvarying with the changes of the tide ; a precious 
gift, as but for it in a few years the absolute levels of our great national sur- 
veys would have become a delusion. In Ireland, for example, they referred 
to the low-water of spring-tides; a mark which could not be recovered, as 
it varies both with time and place. I know not whether this has been yet 
corrected, but I trust it soon will, as Airy’s observations afford the data. It 
would be tedious to tell you all of this kind that we have effected; and I 
leave the subject, with a reference to one more example,—the investigation 
of the motion and nature of waves which we owe to Mr. Scott Russell, 
These lead by an unexpected line to one far more interesting in a practical 
view, the resistance and the furm of ships. On this subject it appears that 
valuable information has been collected for us; and it cannot but be matter 
of regret that materials obtained at so great an expenditure of money (more 
than 1000/.), of labour and thought should remain unavailable, especially 
considering the present imperfect condition of naval architecture in reference 
to science. In many instances we have aided inquiries of inestimable value, 
