848 
POPULAR SCIENCE REVIEW. 
Gyrencephala, and that the hippocampal commissure is the rudiment of the 
corpus callosum, show, notwithstanding his bitterly and painfully personal 
attacks on Messrs. Huxley, Rolleston, and Flower, that he has seen the 
necessity of giving his definitions a greater degree of elasticity than they 
formerly possessed. 
If we could remove the personalities of controversy, and the hypotheses 
of transcendentalism, in which the present work abounds, it would be all 
that we could wish. As it is, it is the most comprehensive and best illus- 
trated treatise on comparative anatomy which has yet been produced in 
England. 
STAR-MAPS* 
A GOOD series of star-maps has long been the desideratum of both 
amateur and professional astronomers. The publications hitherto 
chiefly employed have been those of the “ Society for the Diffusion of Useful 
Knowledge,” and of Mr. Johnstone’s “Atlas of Astronomy.” But neither 
of these possessed the requirements of the student, and Mr. Proctor has 
therefore done good service in the construction of the maps which Messrs. 
Longmans have issued. To those of our readers whose study of astronomy 
has been confined to the “ celestial globe,” that terror of the school-boy, it 
may be necessary to say a word or two in reference to the term Gnomonic 
j projection , the plan on which Mr. Proctor’s maps are constructed. The 
“ celestial globe ” does not convey a true idea of the relative positions of the 
fixed stars, from the circumstance that the observer is supposed to look at 
the heavens from some point billions of miles away from the surface of the 
earth. Now, as the position of the observer is really upon the earth, and 
not away in space, it is clear that for a proper representation ef the heavenly 
bodies the observer should be placed in a huge hollow globe, upon the 
transparent walls of which the meridians, parallels, and stars are depicted. 
This is a popular way of putting the difficulty, which has been partially 
overcome in Mr. Proctor’s maps. But since an apparatus such as we describe 
would be more costly than convenient, a substitute having its principal 
advantages has been sought for and found. If we suppose the centre of 
such a sphere as that we have been describing to be a brilliantly luminous 
point, and if we place the globe upon, let us say, an immense sheet of card- 
board, we shall have a series of shadows formed (Gnomonic projection) on 
the card, in accordance with the markings of the heavenly bodies. Of course, 
the shadows so produced will correspond only to one part of the sphere ; but 
by circumscribing the sphere by a number of pieces of card-board, so as to 
form an even twelve-sided figure — in fact, a dodecahedron , — we shall perceive 
the shadows of all the stars ; convert those shadows into fixed marks, and 
we have Mr. Proctor’s maps before us. In all such projections there must 
* “ The Stars, in Twelve Maps, on the Gnomonic projection, collected in 
duplicate in Four Plates.” By Richard A. Proctor, B.A. Longmans & 
Co. 1866. 
