Zht ^^opular Science jBtetuo 
AND 
BOSTON JOURNAL OF CHEMISTRY. 
Volume XXIV. 
BOSTON, JUNE, 1890. 
Numher 6. 
CONTENTS. 
Pamiliar Science.— Scientific Recre.itions . Si 
The Eiffel Meteorological Observatory . . 8i 
Review ot'Mr. Alfred Russel Wallace's 'Dar- 
winism" 82 
Theories on the Formation of the Earth . . 83 
Foster's Flat 84 
Scientific Brevities 84 
Practical Chemistry and the Arts. — Hints 
to Intending Amateur Photographers . . 85 
A Chinese Seed-Planter 85 
Practical Recipes 85 
The Out-Door World. — A Corresponding 
Geological Chapter 86 
A Course in Mineralogy ....... 86 
A Wonderful Record 87 
Influence of the A. A. on School Teaching . 87 
Exchange Notices 87 
Chapter Addresses, New and Revised ... 87 
Convention of the Massachusetts Assembly . S7 
The A. A. Hill and Dale Club 88 
Reports of Chapters 88 
Editorial. — Some Curious Effects of Atmos- 
plieric Erosion 90 
Paris Letter 90 
Meteorology for April, 1890 91 
Astronomical Phenomena for June, 1890 . . 91 
Safety in Preparing Oxygen 92 
"The Evolution Club" of Chicago . ... 92 
Qiiestions and Answers 92 
Literary Notes 92 
Medicine and Pharmacy.— The Care of the 
Eyes 93 
Women in Pharmacy 94 
Open-Air Exercise in Consumption .... 95 
The Relief of Deformity from Prominent Ears 96 
Music as a Medicine 96 
Medical Miscellany 96 
Publishers' Column 96 
Ban^iliar Science. 
- SCIENTIFIC RECREATIONS. 
To show the difiercnt conductibility of 
heat of different metals, take two stout wires, 
one of iron and one of copper, heat them 
gently, and rub a piece of paraffine or wax 
over them, so as to give them a thin coating. 
the resulting drop slowly move towards the 
bottle. It will be at once evident that the 
coating on the copper wire melts much faster 
than that on the iron, showing that the former 
is a better conductor of heat. The experi- 
ment may be varied by attaching a grain of 
shot, or any small object, to the wires by a 
bit of wax. If both are placed at the same 
distance from the candle-Hame, the one 
attached to the wire which is the best con- 
ductor of heat will drop first. In this 
connection it may be mentioned that copper 
is almost the best conductor known, both of 
heat and electricity, being only exceeded by 
silver, in a very slight degree. • 
A FRICTIONAL electrical machine can be 
easily extemporized in any well-regulated 
family by pressing the household cat into the 
service of science. Place the legs of a chair 
in four clean glass tumblers to insulate it ; 
obtained without insulating the chair at all, 
but the results are more brilliant when this is 
done. The only drawback to this experi- 
ment is the total lack of scientific enthusiasm 
in the average cat, who is likelv to object 
most strenuously, in the familiar feline man- 
ner, against a repetition of the development 
of electrical energy. The electricity thus 
produced is generated by the friction between 
the hand and the fur, and does not dilFer 
from' that produced by any frictional electric 
machine. Tlie organism of the cat plays no 
part in it, beyond furnishing a coating of dry 
and warm fur from which the mysterious 
form of energy may be proiluced by friction. 
The accompanying illustrations are repro- 
duced from Za Nature. 
fhen support them at one end by a cork 
placed in a bottle, taking care to incline the 
wires a very little towards the cork. Then 
place the other end in the flame of a candle, 
as shown in the illustration, and in a few 
seconds the paraffine will begin to melt, and 
tiicn let the person holding the cat sit on the 
chair, resting his feet on the rounds. Then 
let another person genth' stroke the cat a few 
times, when quite powerful sparks will 
appear in tiic fin" of poor pussy, or may be 
drawn from her nose by presenting the 
knuckle to it ; or they may be drawn from 
the chin or fingers of the person holding the 
cat. It would be dangerous, however, to 
attempt to draw them from the eyes. This 
experiment will succeed best in a dry and 
cool atmosphere, and the hand of the person 
stroking the fur should be warm and free 
from moisture. Very good sparks can be 
THE EIFFEL METEOROLOGICAL 
OBSERVATORY. 
One of the most unique meteorological 
stations in the world is that situated on the 
very summit of the Eiffel Tower in Paris, 
983 feet above the ground, and 1,103 feet 
above the sea level. At the top of the tower 
is a small room, reserved for the use of M. 
Eiffel, the designer of the tower ; and above 
this, situated on a platform only five feet in 
diameter, is a fine collection of meteorologi- 
cal instruments, "both self-registering and for 
direct reading, to which access is obtained 
through the trap-door, O. In addition to the 
usual type of hygrometers, barometers, ther- 
mometers, rain-guages, etc., a novel form of 
weather-vane is shown in the illustration at 
C, and at B an anemometer for measuring 
the force of vertical currents of air, as well 
as the ordinary horizontal form at A. A tel- 
ephone contained in the box T gives direct 
communication with the lower world. 
Although the observatory has been estab- 
lished but a short time, some very interesting 
results have been obtained. It is found that 
the average velocity of the wind is about 
three times as great at the summit of the 
tower as at a station in the city below which 
is about 60 feet above the ground. Another 
curious observation is that regarding the time 
of day when the maximum velocity of the 
wind occurs. In the city itself this occurs 
about I P. M., and at sunrise the velocity is 
the least ; while at the summit of the tower 
the minimum force of the wind is observed 
between 9 and 10 A. M., rising to a maxi- 
mum about 1 1 P. M. These observations 
