Notices respecting New Boohs. 67 



between the climates of the above places, occupied in Miocene 

 times the same position as at present, and performed the same 

 friendly function to Spitsbergen. 



3. The Atlantic Ocean occupied its present position ; and the 

 impossible bridge between Greenland and Europe did not exist. 



Climate in past and present times, aud its influence on the dis- 

 tribution of animal life, is frequently referred to ; and the deduc- 

 tions on the causes of geological climates deserve a careful, if 

 not a critical, consideration. Prom a series of calculations on the 

 effects of sun-heat, earth-heat, and atmospheric conditions as the 

 so]e causes respectively of changes in geological climates, the author 

 gives the following probable conclusions : — ■ 



1. We must reject any solution based upon a change of posi- 

 tion, either in space or within the earth's body, of the axis of rota- 

 tion, within the limits of geological time. 



2. "We must reject any solution based upon the secular cooling 

 of the earth (with a fixed axis of rotation), regarded as the sole and 

 immediate cause of the change of climate. 



3. The chief factor in changes of Geological Climate appears to 

 have been the slow secular cooling of the sun, in consequence of 

 which the earth's surface cooled gradually down. 



Generally speaking, the broad facts and leading principles of 

 Physical Geography, and their explanations, are differently treated 

 than in many other manuals on the subject. 



Practical Plane Geometry. By Joins' William Palliser. 

 Simpkin, Marshall, and Co. 1881. 

 This is an excellent treatise on Constructive Geometry, and far 

 more comprehensive than most elementary books on the same sub- 

 ject. It treats of the straight ]ine, angles, circles, proportional parts, 

 equivalent figures, the generation of various curves (not often 

 introduced into even more pretentious books), and the construction 

 of scales. It is well adapted to the requirements of pupils pre- 

 paring for examination at South Kensington, and the Preliminary 

 examinations for entrance to Sandhurst and Woolwich. The 

 constructions are well drawn, and the directions for reproducing 

 the various problems clear and sufficient. We may reasonably 

 make exception to fig. 6 (p. 7) ; for the points G and H are not 

 mathematically determined. There is, too, a much simpler method 

 of inscribing a square in any triangle than the one given on p. 12, 

 though the latter is perfectly sound and demonstrable. In speak- 

 ing of Representative fractions of plans (p. 59), the author says : — 

 " thus j l 2- attached to a plan would show that the drawing is one- 

 twelfth the real size." If the word drawing be taken to apply to 

 the plan or map as a whole, and not to a given straight line in it, 

 it would do nothing of the kind*. Other equally vague expressions 

 occur in various parts of the book. The introduction to Elementary 

 Solid Geometry might, we venture to think, be omitted without in 

 any way detracting from the value of the book. 



* On the same page 365| ought to be 30 x*V,. 

 F2 



