4 i4 
Notices of Books. 
[July. 
such terms as undulations, vibrations, and waves, and use the 
neutral term undce for waves of all periods, no matter whether 
they manifest their existence by giving rise to luminous, heating, 
or chemical effects. The adoption of some such term would 
clear away many of the paradoxical expressions which are now 
used by authors and lecturers, such as radiant heat, — which is 
not heat until it falls on some particular kind of matter, — dark 
heat, adtinic rays, and so on. 
The sun, as may be imagined, receives a large amount of con- • 
sideration. The latest researches into the constitution of comets 
are well described ; and the way in which recent experiments 
with the radiometer and otheoscope, and Tyndall on “Amyl 
Nitrite Clouds,” bear on this interesting but mysterious subject 
is lucidly explained. 
Mr. Skertchly writes in a plain lucid style, and never disdains 
to use a commonplace word or illustration when it will serve to 
make his explanation plainer. He is an admirable expositor, 
and irresistibly carries his reader along with him by the charm 
of his style and the interest which he excites. The book may 
be read by all classes, from the philosopher and student to the 
intelligent man of culture who desires to gain some insight into 
the latest fadts and theories relating to the physical constitution 
of the Universe. 
Ur As Dictionary of Arts, Manufactures , and Mining. Vol. iv. 
Supplement, by Robert Hunt, F.R.S. London: Longmans 
and Co. 1878. 
The editor of a technological work like Ure’s well-known 
Dictionary must have a thankless task, and may be compared to 
an unsuccessful Hercules trying to stay a perennial hydra. In 
the present instance Mr. Hunt and his able assistants may be 
congratulated on the large amount of success with which they 
have been able to lay before their readers a succindt description 
of the progress made by modern manufacturers up to the end 
of last year, and even beyond it. The anxiety shown by the 
editor to give the latest possible information on every subjedt is 
evinced by the fadt of his having deemed it necessary to publish 
an Addendum to his Supplement, for the sake of giving us the 
discoveries of MM. Picftet and Cailletet, and the newest forms 
of telephone. It must have been with a slight feeling of morti- 
fication that Mr. Hunt must have welcomed the discovery of the 
microphone, just too late to be included in the new volume. 
The system of publishing periodical supplements to such 
works is an excellent one, and has already been adopted with 
great success in the case of the sister book, “ Watts’s Dictionary 
of Chemistry.” 
