38 
POPULAR SCIENCE NEWS. 
[iMarcii, 1S90. 
that vertical objects cast no shadows. He observed 
the inclination of the sun in Alexandria (;2), and 
got the distance from Syene to Alexandria (d) from 
the Egyptian tribute-lists. He then calculated the 
circumference of the earth (it) from the proportion 
,1 : d=i6o° : z° 
His result was 250,000 stadia. We do not know 
what stadium he used, but in any case (the stadium 
is, roughly, an eighth of a mile) his result was a 
creditable one, considering the means he employed. 
To discuss, even briefly, the discoveries and theo- 
ries of Ptolemaius (Ptolemy), would be to write a 
history of astronomy. The chronicle of the science 
for many centuries consists merely of comments on 
liis works. 
The Romans did but little in astronomy. That 
they were not keen observers is sufficiently shown 
by the fact that for nearly one hundred years they 
used a sun-dial brought from Catania in Sicily as a 
public time-piece, without noticing the errors due to 
the height of the gnomon, which was intended for a 
more southern latitude. Their most distinguished 
astronomer was Julius Ctesar, whose reform of 
the calendar is too well known to be more than 
alluded to. 
VI. — PHYSICAL GEOGR.M-IIY. 
Intercourse with Egypt led the Greeks at an early 
period to speculations about the causes of the rising 
of the Nile. The great traveller and historian, 
Herodotus, mentions three views which were cur- 
rent in his time.. Two, he says, are hardly worth 
mentioning, while the third (that it is caused by the 
melting of great quantities of snow) he objects to, 
oi»account of the heat of Libya, which would make 
the existence of snow impossible. The real expla- 
nation had its advocates in very early times. The 
alluvial formation of the Nile delta is also referred 
to by Herodotus. 
Earthquakes, which have always been common in 
Greece, early became the objects of investigation. 
Anaximander thought them caused by rifts in the 
earth, the result of long droughts; while Anax- 
agoras believed that masses of air imprisoned in the 
earth and trying to force their way out, were the 
cause of these disturbances. Aristotle agrees with 
this latter theory. Aristotle also considers the 
question of the saltness of the sea, which he thinks 
due to chemical changes wrought vby the sun when 
the water is taken up by it. He believes it can be 
got rid of by filtration and boiling. Strabo first 
observed the fall in temperature as the elevation 
increases, and the fact that tree's were confined to 
certain elevations as well as to certain latitudes. 
Among the Romans, Seneca is the foremost 
Avriter on physical geography. In' his A'aturales 
Qucestiones he discusses the erosive force of water, 
both mechanically and chemically. He observes 
that the spring tides are caused by the attraction of 
both sun and moon together. He defines volcanoes 
scientifically, distinguishing them from subterra- 
nean fires. He does not believe that the earth is a 
mass of fire within, but that there are collections of 
fire in dift'erent parts of its crust. On the subject of 
earthquakes he agrees with Anaxagoras and Aris- 
totle, but considers the imprisoned force to be gas 
or vapor rather than air. 
In the science of navigation little progress was 
made, since voyages were only along the coast. In 
the open sea "dead-reckoning" (by course and dis- 
tance) was employed, the distance being merely 
inferred, while the course was got from the constel- 
lations. Lighthouses and beacons are of ancient 
date, and charts were employed at a comparatively 
early period. 
VII. — .MINEK.ALOGY. 
The industrious Pliny was the first to collect the 
results reached on this subject. He knew a great 
many varieties, although, of course, not the metals 
(like platinum, cobalt, nickel,"" etc.) which are Qot 
found in the Grecian and Italian mountains. He 
enumerated most of the signs by which mineralo- 
gists today distinguish different varieties — shape of 
crystals, cleavage, hardness, color, transparency, 
weight, lustre, and grain. 
VIII. — BOT,\NY. 
The Greeks were probably led to the study of this 
science by the Egyptians, who turned their attention 
to it at a very early date. They found a richly 
developed flora in their own country, "hlthough 
many forms of vegetation, associated in our minds 
with the name of Hellas, first found their way there 
from the East, in coiTiparatively late times. The 
natural philosophers were too much taken up with 
the consideration of larger subjects to give much 
attention to the study of vegetable life, but the 
extensive use of plants for medicinal purposes must 
have led to a considerable knowledge of the subject. 
Aristotle wrote a Theory of Plants, which seems, 
however, to deal mainly with the analogies and 
contrasts between plants and animals. Theophras- 
tus of Lesbos, in the fourth century before our era, 
wrote a work in nine books on botany, in which he 
considers the anatomy and physiology of plants, 
and their dependence on climate and cultivation. 
The Alexandrines confined themselves to the rela- 
tion of botany to medicine, and the same is true of 
the Romans. 
IX. — ZOOLOGY. 
The knowledge of the ancients in this branch 
of science was by no means insignificant, and inter- 
est in it was kept up by the chase, and the popularity 
of fights between wild beasts in later Roman times. 
One writer, Aristotle, treats the subject so ex- 
haustively that his successors did no more than 
comment on his work. He knew five hundred dif- 
ferent varieties of animals, not all of which can be 
exactly identified at the present day. Much that is 
common now-a-days was unknown to him. He 
knew but four species of apes, 9nd nothing at all 
about the man-monkeys. His knowledge of reptiles 
and their geographical distribution is very limited. 
Fishes, from gastronomic reasons, were better 
known. Of the lowest forms of animal life there 
was no knowledge at all in ancient times. Aristotle 
is said to have been fHrnished with material for 
study by his pupil, Alexander the Great, but he 
appears from his description never to have seen an 
elephant or an ostrich. He studied the internal 
structure of animals also, but was hampered in his 
investigations by the preconceived notion that the 
heart was the centre of the nervous system. We are 
unable to learn just How much he did know of this 
branch of the subject, as his special book on The 
Anatomy of Animals is known to us only by its 
title. Pliny gave four books of his Natural History 
to animals, but is in no way original. ^Elian 
describes some new varieties, especially of fishes. 
Solidification of Nitrous Acid. — To solidify 
anhydrous nitrous acid, though still containing 
small quantities of hyponitric acid, there is required 
a temperature of — 52° to — 54*^0., obtained by the 
evaporation of methyl chloride in a current of dry 
air. To obtain anhydrous nitrous acid free from 
hyponitric acid, Fl. Birhans has operated similarly 
to Fritsche, but at a lower temperature. It.forms a 
fine blue liquid, which was solidified only by the 
cold produced by a mixture of methyl chloride and 
carbonic acid in the flocciilent state. This mixture, 
according to the experiments of MM. Cailletet and 
Colardeau, lowers the temperature to 82" below 
zero. 
Tlje Out-Door morUl. 
Edited by HARLAN H. BALLARD, 
President of the Agassiz Association. 
.[P. O. Address, Pittsfield, Mass.] 
It is pleasant to know that the new 
arrangement, by which the Agassiz Associa- 
tion has secured a departnient in this journal, 
and also one for the voungcr memliers in 
Santa Clans, is proving popular. At a 
meeting of the New York Assembly of the 
A. A., a unanimous vote was passed endors- 
ing the plan, and recommending all Chapters 
to appoint committees to solicit subscriptions 
from members and friends. This recom- 
mendation has been promptly accepted by a 
large niuriber of Chai^ters, and a veiy grar1f\- 
ing addition has already been made to the 
readers of both these excellent magazines. 
Mr. W. T. Dcmarest, President of the Man- 
hattan Chapter, No. 20, of New York, one 
of our oldest and strongest branches, writes : 
"As President of the Manhattan Chapter, I 
wish to assure you that your plan has our 
hearty approval, and tlwt we sliall do all that 
in us lies to make it a success." 
We wish every Chapter, and each member, 
to take a personal interest in " IMie Out-Door 
World," and feel, in a measure, responsible 
for it. Let each be "on the lookout" for 
interesting facts, particularly such as come 
under his own observation ; and let him send 
us as promptly as possible an accurate state- 
ment of whatever he finds that is ciuioiis or 
new to him. Whenever you can add to yoiu" 
notes, pictures of the t>bjects or phenomena 
described, it will greatly cniiance their value. 
These pictures may be photographs, line- 
drawings in india-ink, — w hich are the best if 
well done, — or pencil sketches, from which 
our artist may "catch the idea." It is a good 
plan to carr}- a note-book in the pocket, and 
thus be ready to jot down notes of what you 
see at the time you see it. Then, if you can 
send them to us the same day, so nuich the 
better. 
Mr. Fred E. Keay, one of our wide- 
awake members, is engaged in a work which 
may well be imdertaken by others, each in 
his own neighborhood. "I have in mind," 
he writes, "to make a set of photographs of 
our native trees, selecting as fine representa- 
tives of each as I can find." If this plan 
could be thoroughly carried out, and if to the 
photograph of the tree, were added photo- 
graphs of details, — such as leaves, flowers, 
fruit, bark, grain of wood, insect visitors, 
attached ne.sts, etc., — a valuable contribution 
to science would result. 
A WORD of special welcome must be 
spoken to Chapter 771, of Adelaide, Austra- 
lia, and also to the two Russian Chapters, ' 
