May 30, 1912] 
NATURE 
317 
“partial” correlation, which promises to be so 
important in the analysis of correlation results. In 
the discussion of the psycho-physical method of 
constant stimuli, it is unfortunate that a reference 
is still made to a method for doing without 
Gauss’s formula in which the mean of a frequency- 
distribution is “corrected” or “adjusted.” It has 
been known for some years that the mean of a 
frequency-distribution needs no adjustment. One 
must hasten to add, however, that the text of this 
chapter on the psycho-physical methods is ex- 
ceptionally clear and sound, and is undoubtedly 
the best elementary account we have of a rather 
difficult part of psychology. 
A JOURNEY TO CANADIAN BARRENS. 
The Arctic Prairies: a Canoe Journey of 2000 
Miles in Search of the Caribou; being the 
Account of a Voyage to the Region north of 
Aylmer Lake. By Ernest Thompson Seton. 
Pp. xvi+415. (London: Constable and Co., 
Ltd., 1912.) Price 12s. 6d. net. 
T need scarcely be said that Mr. E. Thompson 
Seton’s book makes wholesome and exhilarat- 
ing reading, instinct throughout with its author’s 
sympathy and enthusiasm for wild life. 
zesthetic embroidery, while enjoyably present, is 
kept subordinate to the sincerity and accuracy 
required of the true naturalist. A six months’ 
canoe-journey was made by the author in the open 
season of 1907 down the Athabaska River and 
through the forested country of its lake and river 
continuations to Lakes Clinton-Colden and Aylmer 
of the Barren Lands, in lat. N. 64°, a distance, 
there and back, of some 2000 miles or so; and this 
is the record of it. 
Geographically, the journey was not of high con- 
sequence, though Mr. Seton was able to make 
some additions and corrections to the previous” 
maps, particularly in respect to Lake Aylmer. 
Nor is there any startling incident of travel to 
relate, for the adventures and misadventures were 
just those of every voyageur into the northern 
wilderness; indeed, the author’s capability is best 
shown by the relative ease with which his task was 
accomplished. Neither is this a hunter’s book; 
the sportsman-reader will’ be fretted with the same 
sense of wasted opportunity that was expressed by 
Mr. Seton’s Indian and half-breed companions, 
who found it unaccountable that a man should 
follow the chase so laboriously for the thin satis- 
faction of seeing animals. Because of these un- 
usual features—and of the author’s ever-artistic 
touch—the narrative is more entertaining than 
most of its type. 
NO. 2222, VOL. 89] 
| fair regularity ten years apart” (p. 
| form of a simple 
The |} 
In a highly interesting chapter on the ebb and 
flow of animal life, the author discusses a series 
of graphs which he has compiled from the records 
/of the Hudson Bay Company for the years 1821 
to 1908, showing the number of pelts of fifteen 
different fur-animals that have been dealt with 
annually during this long period. From these 
statistics certain deductions are drawn, notably 
that “the high points for each species are with 
tog). In 
another chapter Mr. Seton deals categorically with 
the interdependence of the rabbit (Lepus ameri- 
canus) and the lynx, stating that the former in- 
creases rapidly to a maximum in spite of its many 
voracious enemies, and is then suddenly thinned 
out nearly to vanishing point by epidemic diseases 
known collectively as “plague,” with secondary 
consequences almost equally disastrous to the lynx 
population. 
Most commendable is the author’s ingenious 
way of treating a recurrent subject that would 
make “painful and dreary reading ”’ if oft repeated. 
He asks the reader to allow him, once and for all, 
| a chapter on that terror of the northern wilds, 
the mosquito; and later allusions to it take the 
“see chap. ix.” The idea might 
profitably be extended by the introduction of 
standing references of this kind for use in travel- 
literature in general. 
Some vigorous drawings, as well as photo- 
graphs, of animal life are reproduced as plates, 
and the book is further illustrated by 125 sketches 
in the text, which have the live touch that no 
photograph can convey. 
The appendices include full lists (with notes) of 
the mammals, birds, and plants that were col- 
lected or seen; a short list of insects; a ‘“‘buffalo 
summary,” from which it appears that more of 
these animals survive in the wild state than had 
been supposed; and a (reprinted) plea for the 
introduction of the yak as a range-beast for the 
| north-west. 
ELEMENTARY PRACTICAL PHYSICS. 
| 4 Laboratory Note-book of Physics. By S. A. 
McDowall. Part i., pp. viiit+166. Part ii., 
pp. viii+126. (London: J. M. Dent and 
Sons, Ltd:, n.d.) Price 2s. 6d... net7 each 
part. 
HOSE who have to deal with large classes 
in practical physics know how difficult it 
is for the demonstrator to set and maintain the 
class going without some aid in the form of printed 
instructions, such as note-books or separate slips 
relating to each experiment. This plan is, how- 
