1875.| Notices of Books. 253 
contains some interesting remarks concerning the colours of the 
sky, which question has been debated any time since that of 
Leonardo da Vinci. He and many subsequent writers attributed 
the celestial blue to a mixture of the light reflected from terres- 
trial substances with the darkness of space. Goethe, in his 
‘‘ Farbenlehre,” revives the same idea: he points out that, when 
we look through a turbid medium which is illuminated, at a black 
background, the medium appears to be blue; while light itself, 
viewed through such a medium, is yellow or red. He points 
out also the blueness of distant mountains, and of smoke seen 
in particular lights. The author then alludes to Tyndall’s ex- 
periments, and with him concludes that the blue colour of the 
sky is due to the presence of extremely minute particles of water. 
On pp. 80-81, we find a few inaccuracies of printing; thus tem- 
peratures are written like degrees of arc, 17° 6' F. 50° 4', and 
(p. 81) the minus is omitted in stating extremes of cold:—53°, 58°. 
The table pp. 82-83, is also printed rather carelessly in the case 
of the Latitude column. Among the low European temperatures 
we find —5° F. near London, — 10°5°in Paris, —22°in Hamburg, 
—37° in St. Petersburg, —44° in Moscow, and — 58° at Enontekis 
in Lapland. The records of several winters in Europe are most 
surprising; it is said that in 860 and 1234 the Adriatic was 
frozen over, and goods were transported from Venice to the 
opposite Dalmatian coast, over the ice. In 1364 all the rivers 
of France were frozen over, and the ice on the Rhone was 
15 feet thick. The winter of 1788-89 appears to have been one 
of the severest onrecord. The Rhone was frozen over at Lyons, 
and the port of Ostend was closed by ice; and the Thames was 
frozen as far as Gravesend. As to European extremes of heat, 
we learn that in 1793 the thermometer in London registered 
89° F., and in Paris, ro1° F.; in each instance in the middle of 
July. In 1852, the thermometer in London rose to g5° F. in the 
shade on July r2th. 
In the seventh chapter, ‘‘On Winds,” the author devotes 
several paragraphs to an account of the Tower of the Winds in 
Athens, using always the past tense, ‘‘ Boreas was represented,” 
other winds ‘‘ were represented.” But there is no need for this. 
We may use the present tense for many long years to come; the 
Tower of the Winds is quite perfect, and is of comparatively late 
erection, that is to say, 100 B.c. The description of the mon- 
soons, and the causes which produce them, is as complicated 
and difficult to understand as it is in every book in which we 
have seen them mentioned and described. An interesting account 
of a thunderstorm seen from a balloon, and a “side view of a 
storm,” will be found in the fourteenth chapter. We notice in the 
woodcuts the usual error in regard to lightning, which is made 
pointed, whereas, as Faraday pointed out, if we could see the 
end of the flash at all, it would be at least as thick as the rest 
of the flash. Remarkable examples are recorded of the power of 
