e
hundred years ago there was no chemical science worthy of the name, no
knowledge of the constitution of plants or the properties of light and
heat. The old philosophers considered light and heat to be fluids,
which passed out of substances when they were too full. Count Rumford
showed that motion was convertible into heat, but did not trace the
motion to its source, so far as we know, in the sun.

It is only forty-six years since Professor Joule first demonstrated
the mutual relations of all the manifestations of nature's energy.
Thirty-nine years only have passed since he announced the great law of
the convertibility of force. He constructed a miniature churn which
held one pound of water, and connected the revolving paddle of the
churn with a wheel moved by a pound weight, wound up the weight, and
set the paddle in motion. A thermometer detected the change of
temperature and a graduated scale marked the distance traversed by the
descending weight. Repeated experiments showed that a pound weight
falling 772 feet would raise the temperature of water one degree, and
that this was an unvarying law. This was transferring gravitation to
heat, and the law held good when applied to electricity, magnetism,
and chemical affinity, leading to the conclusion that they were
severally manifestations of one universal power.--_Congregationalist._

* * * * *

EARLY ELECTRIC LIGHTING.

The opening of the new station of the Electric Lighting Co., of Salem,
Mass., was recently celebrated with appropriate festivities.

Among the letters of regret from those unable to attend the opening
was the following from Prof. Moses G. Farmer:

"ELIOT, Me., Aug. 5, 1889.

"_To the Salem Electric Lighting Company, Charles H. Price,
President_:

"GENTLEMEN: It would give me great pleasure to accept your kind
invitation to be present at the opening of your new station in Salem
on the 8th of this present August.

"It is now thirty years since the first dwelling house in Salem was
lighted by electricity. That little obscure dwelling, 11 Pearl Street,
formerly owned by 'Pa' Webb, had the honor to be illuminated by the
effulgent electric beam during every evening of July, 1859, as some of
your honored residents, perhaps, well remember. Mr. George D. Phippen
can doubtless testify to one or more evenings; Mr. Wm. H. Mendell, of
Boston, can also add his testimony; dozens