to read the movements of matter.

It should be recognized that Professor Young, of [Page 54]
Princeton, is the most successful operator in this recent realm of
science. He already proposes to correct the former estimate of the
sun's axial revolutions, derived from observing its spots, by the
surer process of observing accelerated and retarded light.

Within a very few years this wonderful instrument, the spectroscope,
has made amazing discoveries. In chemistry it reveals substances
never known before; in analysis it is delicate to the detection of
the millionth of a grain. It is the most deft handmaid of chemistry,
the arts, of medical science, and astronomy. It tells the chemical
constitution of the sun, the movements taking place, the nature of
comets, and nebulæ. By the spectroscope we know that the atmospheres
of Venus and Mars are like our own; that those of Jupiter and Saturn
are very unlike; it tells us which stars approach and which recede,
and just how one star differeth from another in glory and substance.

In the near future we shall have the brilliant and diversely colored
flowers of the sky as well classified into orders and species as
are the flowers of the earth.




[Page 55]
IV.

CELESTIAL MEASUREMENTS.