the forest. The event which produces a great sensation has often only
insignificant consequences; while another, which seemed at the outset
of the least importance and little worthy of note, has in the long run
a widespread and deep influence.

If, however, we deal with the history of a positive discovery,
contemporaries who possess immediate information, and are in a
position to collect authentic evidence at first hand, will make, by
bringing to it their sincere testimony, a work of erudition which may
be very useful, but which we may be tempted to look upon as very easy
of execution. Yet such a labour, even when limited to the study of a
very minute question or of a recent invention, is far from being
accomplished without the historian stumbling over serious obstacles.

An invention is never, in reality, to be attributed to a single
author. It is the result of the work of many collaborators who
sometimes have no acquaintance with one another, and is often the
fruit of obscure labours. Public opinion, however, wilfully simple in
face of a sensational discovery, insists that the historian should
also act as judge; and it is the historian's task to disentangle the
truth in the midst of the contest, and to declare infallibly to whom
the acknowledgments of mankind should be paid. He must, in his
capacity as skilled expert, expose piracies, detect the most carefully
hidden plagiarisms, and discuss the delicate question of priority;
while he must not be deluded by those who do not fear to announce, in
bold accents, that they have solved problems of which they find the
solution imminent, and who, the day after its final elucidation by
third parties, proclaim themselves its true discoverers. He must rise
above a partiality which deems itself excusable because it proceeds
from national pride; and, finally, he must seek with patience for what
has gone before. While thus retreating step by step he runs the risk
of losing himself in the night of time.

An example of yesterday seems to show the difficulties of such a task.
Among recent discoveries the invention of wireless telegraphy is one
of those which have rapidly become popular, and looks, as it were, an
exact subject clearly marked out. Many attempts have already been made
to write its history. Mr J.J. Fahie published in England as early as
1899 an interesting work entitled the _History of Wireless
Telegraphy_; and about the same time M. Broca published in France a
very