1864. | 
instead of the mark being continu- 
ous like that of a pencil, it rather 
resembles a string of beads. The 
cause of this lack of continuity is 
to be found in the movements of 
the Earth’s atmosphere. Or, if the 
eye is placed at the eyepiece of the 
telescope, and the edge of a planet 
or the moon watched, it is found to 
present a wavy outline instead of a 
sharp disc-like appearance. Any 
point in the surface, too, is seen to 
have a rapid vibratory motion. 
Although the eye can emancipate 
itself to a certain extent from these 
disturbances, a photographic plate 
cannot. Every point tends then to 
assume a greater size and less dis- 
tinctness than it should have, and 
if the night on which the trials are 
being made is very unsteady, the 
smaller details are so confused to- 
gether that the picture is worthless. 
Occasionally, however, very still 
nights occur, when photographs of 
great beauty may be taken. In the 
interval between March and De- 
cember, 1863, three such nights 
occurred, and on one of them the 
negative for the 3-foot was ob- 
tained. 
It has been stated that there are 
no insuperable obstacles to the pro- 
duction of perfect celestial photo- 
graphs,—that is, such as realize the 
full optical power of the telescope 
used. The atmospheric difficulty 
may be successfully combated by 
removing a large reflector from near 
the level of the sea to a consider- 
able altitude, where a great part of 
the atmosphere is left behind. It 
seems to me that a suitable place 
for such a purpose would be the 
rainless west coast of South Ame- 
rica, somewhere near the equator. 
Improvements, too, are continually 
being invented in photographic pro- 
cesses, and a considerable step is 
made when we find out what it is 
that we need. Quick methods are 
not so much required as those which 
will yield grainless pictures on struc- 
tureless films, and unless the time 
of exposure could be so much short- 
ened as to be buta small fraction of 
a single atmospheric pulsation, no 
Notes and Correspondence. 
387 
particular advantage would be gained 
by their use. 
The inducements to amateurs to 
prosecute the study of celestial 
photography are very great, and the 
apparatus required is such as any 
one of a mechanical turn may make. 
A great deal can and will be done 
in this branch of astronomy; and 
animated by the hope that many 
others may be induced to cultivate 
it, I have written the detailed ac- 
count in the Smithsonian Contri- 
butions. 
Henry Draper, M.D., 
Professor of Natural Science in the 
University of New York. 
The Brazilian Coal-fields. By Edward 
Hull, B.A., F.GS. 
THE immense empire of Brazil, oc- 
cupying one-third of the continent 
of South America, with an area of 
upwards of 3,000,000 of square 
miles; considerably larger than 
Russia in Europe ; watered by the 
largest river in the world, which 
with its tributaries is navigable for 
many hundred miles from its mouth; 
its western bounds stretching to 
the spurs of the Andes, and its 
eastern washed by the waves of 
two oceans—such a country as this 
would appear fitted to occupy the 
foremost rank amongst the na- 
tions of the Western hemisphere, 
provided its boundless resources 
were turned to account by an intel- 
ligent people, and civilization were 
advanced by wise laws. It is satis- 
factory to reflect, that while most 
of the surrounding republics—the 
shattered limbs of Spanish America 
—are tossed on the waves of anarchy, 
Brazil enjoys a peaceful government 
under a constitutional monarchy ; 
personal freedom with political se- 
curity ; monarchical principles com- 
bined with popular rights. We 
notice these points in the govern- 
ment of Brazil, because they afford 
the highest guarantee of national 
progress, and the development of 
industrial pursuits. Nor are the 
raw materials necessary for the at- 
tainment of a high position amongst 
