MAGAZINE OE SCIENCE AND AIIT. 
243 
THE AGE OP DISCOVEKP. 
The progress .of mechanical invention has 
been so rapid during the past three or four 
years, that it may be useful and interesting 
to refer to a few of the triumphs that have 
been achieved, and to speculate on the 
future direction that the researches of 
human ingenuity will take. 
The experience that has been gained 
by those who have attentively watched 
the first appearance and gradual deve¬ 
lopment of the mechanical marvels of 
the day, may, without their laying claim 
to any power of prophecy, be applied to 
the prediction of some at least of their 
successors. It is a very rare occurrence 
that a new discovery exhibits to the world 
at once all its future proportions. Those 
who some twenty years ago watched with 
incredulity the building of an iron barge in 
England for the carriage of coal, and have 
successively seen the construction of larger 
and still larger iron vessels, until they have 
culminated in th cLeviathan, would scarcely 
have been able to claim the title of prophet 
had they predicted it, for the first step had 
been taken, and the result was within the 
bounds of probability. So also with the 
electric telegraph. When Oersted de¬ 
monstrated the rapid passage of the electric 
fluid through a metallic conductor, and its 
instantaneous deflection of the distant 
needle, and when once it had been found 
to be a reliable fact, the vast results might 
have been foreseen without any super¬ 
natural sagacity. The commencement of 
the art of photography is within the me¬ 
mory of most of our readers, and they will 
call to mind how gradual and how constant 
has been its progress until the present time, 
when it bids fair to drive the artist and the 
engraver out of the field. Even now 
books of biography and of travel are pub¬ 
lished in England, all the illustrations of 
which are photographs taken directly from 
the objects they propose to represent. 
Our shop windows in this city exhibit 
photographic pictures of the scenery of 
tins beautiful harbour that no engraver, 
however skilful, could equal, and for a few 
pence the native of England may procure 
as perfect an image of the loveliest scenes 
of his native land as ever was depicted on 
the retina of his own eye. These wonder¬ 
ful results were, no doubt, dimly foreseen 
by Fox Talbot, Niepce, and Daguerre, 
when first they succeeded in fixing the 
transient image on the mirror or the paper, 
No. 12, May, 1858. 
and although they appeared impossible to 
most minds, they now are seen to be the 
natural consequence of the discovery that 
was then made. 
Let us now see if there is any other 
great discovery, or rather development of 
a great discovery looming in the future. 
We think there is, and would direct the 
attention of our readers to the Times 
newspaper of December 26th, 1857, where 
there is a full and elaborate description of 
Allan’s Electro-Magnetic Motive Engine, 
which seems likely', at no very distant day, 
to supersede the Steam Engine itself. The 
production of sustained power by electro¬ 
magnetism has long been a problem to 
scientific men, and the Government of 
France, jealous perhaps of the great wealth 
and importance that England has achieved 
by means of the Steam Engine, offers a 
reward of 50,000 francs, or £2000 to the 
individual who shall discover a method of 
rendering the voltaic pile applicable eco¬ 
nomically to industry as a source of heat 
or light, or to chemical or mechanical 
science, or to medicine. 
Mr. Allan claims to have made it capable 
of producing mechanical force, and we ex¬ 
tract the following account of his discovery 
from the “ Year Book of Facts” for 1858. 
We may' mention that his electro-magnetic 
motive engine has been referred to a com¬ 
mission, consisting of the most eminent 
scientific men in France, and that they 
have reported most favourably upon it to 
the Emperor. It is much to be regretted 
that the British Government is never found 
to be the first to come forward to reward 
and encourage inventors, who, like the 
prophets of old, are “ not without honor 
save in their own country.’’ 
“ Among the objections made to electro-magnet¬ 
ism, as a producer of useful power, have been, 
first, the cost of the power, and, secondly, the 
shortness of the space through which the power is 
exerted, or, in other words, the want of adequate stroke 
or motion in the force. The power of electricity, when 
applied in the form of an electro-magnet, is wonder¬ 
fully great from comparatively small means, but its 
dynamic power decreases so rapidly through interven¬ 
ing space, being ‘inversely as some unascertained power 
of the distance much greater than the square,’ that the 
range of the maximum effect, or valuable portion of tho 
motive force with a consequent minimum of consump¬ 
tion extends to so small a distance as to be of no real 
value in mechanics. The great problem to solve has 
been to contrive such an arrangement of parts as to 
conveit this maximum of the motive force, through a 
range, although unavailable in itself, into stroke, or to 
give it such an extent of motion as to make it of prac¬ 
tical value as a motive power. Air. Allan’s electro¬ 
magnetic engine has achieved many of these desiderata. 
He has utilized all his power—he has obtained length 
of stroke. By this invention the maximum portion only 
