, glycerine, and leaves
the grease as an acid grease. This same effect has been noticed in some
steam boilers, where the same water, without admixture of fresh, has
been used over and over again with surface condensers. Then, again,
large rotating chemical furnaces have been introduced; and improved
glass furnaces--particularly tank glass furnaces, in which the batch is
put in at one end, and the working holes are toward the other end--have
cheapened the actual production of glass, and are being worked largely
on the Continent, and to some extent in this neighborhood. Toughened
glass has made some progress for certain purposes. Besides the improved
and extended use of glass in lighthouse illumination, it has again
been pressed into our service for other purposes, through our greatly
extended knowledge of the laws of optics.
Spectrum analysis has become of practical use, and photographs of the
various Fraunhofer lines in the spectrum have been taken as permanent
records of each experiment. That such extended knowledge should have
been developed by that one little instrument, the lens, is but natural;
for the lens is at once the means by which we discover the extreme
magnitude of some portion of the infinite works of the Almighty in the
architecture of the heavens, and by which we appreciate to some extent
the extremely minute markings of a diatom that one cannot see with the
naked eye.
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