430 REVIEWS. 
have learned that Zentmeyer does make glasses, and that one of the 
Tolles' stands which he had seen was furnished with an excellent ob- 
jective by Zentmeyer. In the notice of Zentmeyer's stand the most im- 
n his notice of Grunow's instruments he particularizes an inverted 
microscope, the peculiarity of which was a movement by friction cibis 
an invention of Tolles, and which he (Hagen) had seen various modifica- 
tions of on several of Tolles’ instruments, in particular the first one in 
which it was ever introduced; yet he failed to notice it there. 
It may, perhaps, be urged for Dr. Hagen that these things are trivial, 
and to some they may look so; but they constitute Dr. Hagen's paper; 
the aggregate of the trivialities makes about the whole. Dr. Hagen fails 
throughout all his papers to appreciate the difference between magnifying 
power and quality. 
ith a patronizing air that is “ nearly comical,” viet reading the paper, 
he compliments the artists in these words: ‘Messrs. Tolles and Wales 
re no doubt artists of asi first water, constantly abides tá advance 
and enlarge their science 
r. Hagen admits that he has not exhausted his subject, and promises 
to renew it; it is to be hoped that he will, and that when he does he will 
spare no pains to make himself thoroughly acquainted with it; if he en- 
deavors to do that, all our judi eu will cheerfully assist him. — C. S. 
ALASKA AND ITs Resources.* It is not often that an expiration is able 
and therefore, undertook to carry out the remainder of the explorations 
which were only half completed when the telegraph eT reunion 
the enterprise. The author was thus left alone for one and suc- 
ceeded in completing the survey of the Yukon Valley, zal dine except 
by the natives. As a thorough and reliable account of Alaska, with its 
o 
fee of th: 
elegant book, and that it is the fruits of American pluck, enthusiasm, 
and scientific zeal. 
Many of the scientific results obtained by Mr. Dall have been already 
published in the NATURALIST, and the great value of his discoveries in a 
of onal 
a, we are struck ra the earnest endeavor of the author to 
*By William H. Dall. Lee and Shepard, Boston, 1870. 8vo, pp. 627. With a map and nue 
merous illustrations. $7.50, 
