194 Reviews. [ Jan. 
sun ina hyperbola, and that it became visible at a point in the heavens 
near the star y Cephei. For the elements of this determination we 
must refer the reader to the little work under review. 
With regard to the chemical composition of fire-balls, Dr. Heis has 
nothing new to tellus. The recent discovery of hydrocarbons, graphite, 
and free sulphur in stones which have fallen, may lead to the supposi- 
tion that some are wholly combustible in very attenuated air, and we 
may thus account for the phenomena of falling or shooting-stars ; while 
in others the mineral matters may predominate, and these sometimes 
exploding with detonation, fragments fall to the earth constituting 
meteoric stones. : 
Respecting the origin and destination of the Meteors and fire-balls 
we have, of course, no information, and the votaries of modern science 
and of ancient poetry will still continue variously to regard them as 
fresh fuel for our flaming sun, or fragments of a shattered world. 
MILLS AND MILLWORK.* 
To the minds of laymen the vocation of engineering is not so obviously 
cut up into distinct departments as the better known and older profes- 
sions. While time and the experience which each of us must encounter 
teach all men to distinguish, with some approach to accuracy, between 
the many distinct provinces into which the practice of medicine and 
that of law are divided, there are comparatively few persons not con- 
nected with engineering who are aware that the same division of labour 
which characterizes each of the three so-called learned professions 
may be found to regulate and aid the labours of the engineer. The 
two main lines of the calling are pretty well known under their relative 
names of Civil, and Mechanical Engineering ; but out of these, and 
especially out of the latter, there spring numerous entirely distinct 
branch lines, each leading and ministering to its own special industry, 
and each (to carry out our figure) presided over by a distinct staff of 
management with widely different functions. 
The civil engineers being a more purely professional class than 
their mechanical brethren, naturally deal with a wide range of matters, 
and do not greatly tend to split up into specialities ; but the mechani- 
ian being generally a practical man who lives by producing as well 
as scheming machinery, soon finds that his business, to be made pro- 
fitable, must be confined within comparatively narrow limits. 
Hence there arises an immense varicty of machine makers, all in- 
cluded under the generic title of mechanical engineers, a body amongst 
whom, taken as a whole, there exists an astonishing amount of practical 
experience and theoretical knowledge ; but each having his own speci- 
ality out of which it is seldom his wish or his interest to travel. 
This is, however, quite a recent state of things in the profession. 
* ¢Mills and Millwork.’ By W. Fairbairn, Esq., C.E., LL.D., F.R.S., F.G.S., 
&ec. 2 vols. Longmans. 
