Geological Survey of Great Britain. 239 
cial labours of the members of the Survey, are contained in 
the Memoirs of the Geological Survey of Great Britain and of 
the Museum of Practical Geology in London. Two volumes of 
this collection, the second in two parts, have been published 
in large octavo. The numerous woodcuts interspersed in the 
text, the splendid engravings of fossils, and the many illus- 
trations of every kind, increase not a little the utility of these 
excellent works. 
* * * * 
We must add among the results, the extensive collections 
in the Museum, which, in connection with the lectures it is 
proposed to give during the winter, will greatly contribute to 
the spread of useful knowledge through the country. The 
investigation of English building-stones, and the results thus 
obtained were above alluded to. Lastly, it must not be over- 
looked, that one of the greatest advantages of the Institution 
consists in the explanations which every person interested in 
mines or manufactures most readily receives there, upon all 
scientific questions having any bearing on his branch of busi- 
ness. 
I cannot close this division of my report without thankfully 
acknowledging the liberality with which Sir Henry De la 
Béche, as well as all the eminent savans employed in the work 
under his direction, allowed us to enter upon all the details 
of the same. We have to thank their friendly instruction for 
the more accurate acquaintance with an Institution, which, 
i= in magnificence of arrangement, in talented execution of the 
proposed plan, and in abundance of results, which are as im- 
portant for science as for practical life, far surpasses all simi- 
lar undertakings that have hitherto been carried out, and 
will long serve as a model for geological investigations in 
other portions of the globe. 
On the Tides, By Wiuu1AM GALBRAITH, M.A., F.R.A.S., 
Teacher of Mathematics. Communicated by the Author. 
In my article in the last Number of this Journal, I endeavoured 
to point out the proper method of analysing a register of the tides, 
and deducing the necessary results when the sun and moon were at 
their mean distances from the earth, and in the plane of the equator. 
