The times. [volume] (Washington [D.C.]) 1897-1901, 1901-01-13

the first. Photographic prints were pro-
duced by Wedgewood and Davy.
oBSERy ATORIES.
It has been stated that at the beginning
of the century there were no permanent
ohservatories either in the southern hemi-
! sphere or in the United States. The end
of the century finds US with 2G0 observa-
! tories all told, of which fourteen are south
of the equator and forty-seven in the
United States, among which latter are the
best equipped and most active in the
world.
The observatory of Parramatta was the
first established On 1s2D in the southern
hemisphere. This was followed by that at
| the Cape of Good Hope in 1923. OF the
more modern southern observatories from
which the best work has come We may
mention Cordoya the seat of Gouds i'm
poTtant investigations, established in 1868,
and Arequipa, dependency of Harvard,
whence the spectra of the southern stars
have been secured, erected still more re-
Gently dsSD.
/ believe, but 1 do not know. that the
large number of American observatories
! have radiated from Cincinnati where in
| consequence of eloquent appeals. both by
voice and pen. from Mitchell, then profess
sor of astronomy, an observatory was
commenced in 1915 There can be no doubt
that at the present moment, with the nu-
merous well equipped and active observa-
| tories, and the careful and thorough
| teaching established side by side with
| them, which enables numberless students
| to use the various Instruments, the United
! States in matters astronomical fills the po-
sition occupied by Germany at the begin
ming of the century.
| In Europe special observatories have
been established at Bfeudon, Kensngton,
and Potsdam, so that new astro-physical
enquiries may be undertaken without in
! terfering with the prosecution or extern
sion of the important meFidional work
| carried on at Paris. Greenwich. and Ber-
| lin 4 large proportion of the observa-
| tons made by the Lick and Yerkes OBJ
4 servatorfes in the United States has been
astro-physical.
One of the special enquiries committed
to the charge of the Solar Physics Obser-
yatory at KensingtOn at its establishment
by the British Government had relation to
! the possibility of running home meteoro-
1 logical changes on the earth, especially
those followed by drought and famines in
various parts of the Empire, to the vary
ing changes in the sun indicated by the
ebb and flow of spots on its surface. With
this end in view observations of the sun
| were commenced in India and the Maui
ritius to supplement those taken at Green
wich. AT the same time other daily obser-
vations of sun spots By a different method
were commenced at Kensington-
This kind of work was at first consid-
cred ideally useless; we shall see later on
| what has become of IT.
| IMPROVEMENTS IN TELESCOPES.
The progress in astronomical science
| throughout the closing century has nat
| the advances made both In the optics of
| the telescope and the way in which they
are mounted, either with circles to record
exact times and positions, or made to
move so as TO keep a star or other celes-
tial objects in the field OF view while I'M
der observation. The perfection of Giefini-
ton and the magnitude OF the lenses en-
pIoyed in the modern instrument have
! been responsible for many important dis
| coveries.
Ever since the telescope was invented
Galileo's lens was smaller than those used
in spectacIes-men's minds have been CON
| cenuated on producing instruments of
| larger and larger size to fathom the cos
| mos to its innermost depths.
At the beginning of this century We
were, as we have seen already in possess
sion of refectors of large dimensions; Her
aTf mir
was using in 1901, which had a focal length
Of forty feet was capable of being en-
ployed with high magnifying powers; and
it was the judicious use of these, on &C.
easions when the finest of weather pre-
vailed, that enabled him to enrich so ex-
tensiveIy our knowledge Of tie stellar and
planetary systems. For the ordinary work
Of astronomy, however, especially when
| circles are used, refractors are the more
suitable Instruments. This form buffers
less from the vieissitudes OF weather and
temperature and is therefore more suited
where exact measurements are required.
Toward the end of the eighteenth cen
fury a Swiss artisan. Pierre GuiIiard. after
many years Of patient labor, succeeded IN
producing pure disks of flint glass as large
| as SIX inches in diameter. The modern re-
fracting telescope thus became possible
In 1904 there was started u. Munich the
famous optical and mechanical institute
which soon made its presence felt in the
astronomical world. Reforms in instru-
ment making were soon taken in hand,
and under the leadership of the great Ger
man astronomer, Bessel great strides
were made in instruments Of precision.
Fraunhofer. who had been silently work
ing away at the theory of lenses, and
making various experiments IN the mahu-
facture of glass, was Joined In 1905 by
Guinard. In 1899 Troughton invented a
new method OF graduating circles, accord
ing to Airy the greatest improvement ever
achieved in the art OF instrument making.
In 1874 Fraunhofer successfully CON-
pleted and perfected an object glass of 81
inches In diameter for the Dorpat obser-
vatory. This objective might literally have
been called a giant" for nothing ap-
preaching it in size lad been previously
made.
England. which was at one time the ex-
elusive seat OF the manufacture of refract-
ing telescopes was now completely out
| stripped by both Germany and France
and for this We had to thank the short
sighted policy of the Government. which
had placed an cxorbitant duty on the man.
ufacture of flint glass In 1888 the Dorpat
refractor was ecIipsed by one of fifteen
inches aperture made for the Pulkowa
hofers successors. who about ten years
'