pictures will be of the greatest value, not only in fixing the position at
a given date, but also aiding in the determination of magnitude, color,
variability, proper motion, and even of the orbits of double and multiple
stars, and the possible discovery of new planets and telescopic comets.

Such are some of the many branches of astronomy that are receiving the
most valuable aid at present from photography; but the very value of the
gift that is bestowed should make exaggeration an impossibility.
Photography can well afford to be generous, but it must first be just, in
its estimate of the work that has still to be done in astronomy
independently of its aid; and although the older science points with just
pride to what is being done for her by her younger sister, still she must
not forget that now, as in the future, she must depend largely for her
progress, not only on the skill of the photographer and the mathematician,
but also on the trained eye and ear and hand of her own indefatigable
observers.--_S.J. Perry, S.J., F.R.S., in Br. Jour. of Photography._

* * * * *




ELECTRICITY AS A PREVENTIVE OF SCALE IN BOILERS.


The mineral sediment that generally sticks to the sides of steam boilers,
and the presence of which is fraught with the utmost danger, resulting in
many instances in great injury to life and property, besides eating away
the substance of the iron plate, was referred to in a paper lately read by
M. Jeannolle before the Paris Academy of Sciences, in which the author