C|)c popular Science 0tXas 
AND 
BOSTON JOURNAL OF CHEMISTRY. 
Volume XXIV. 
BOSTON, APRIL, 1890. 
Number 4. 
CONTENTS. 
Familiar Science. — The Magic Cash Box . . 49 
Leaf Mosaics 49 
The Proto-IIelvetes, or Lake -Dwellers of 
Switzerland 51 
Scientific Brevities 52 
Practical Chemistry and the Arts. — Aerial 
Navigation 52 
Aluininium 52 
How Jugs are Made . . .' 53 
State Telephony 53 
Laboratory Notes 53 
The Out-Door World. — Mr. Wight's Course 
in Botanv .54 
Professor Cassedy's Course in Chemistry . . 54 
A New Member of the A. A. Council ... 54 
Chapter Addresses. New and Revised ... 54 
The World's Fair in 1S92 54 
The Isaac Lea Mem»rial Chapter of Con- 
chology 55 
Original Observations by Members of the 
Agassiz Association 55 
Reports from Our Chapters 55 
Alaskan Burial 56 
Editorial. — Some Assumptions of Science . 57 
The Mineral Wealth of New Mexico ... 58 
Paris Letter 59 
Meteorology for February, 1890, with Review 
of the Winter 59 
Astronomical Phenomena for April, 1890 . . 60 
Literary Notes 60 
Medicine and Pharmacy. — The Relation of 
Chemistry to Medicine 61 
A Talk by John Wesley: London, A. D. 1747 61 
Monthly Summary of Medical Progress . . 63 
Medical Memoranda 64 
Publishers' Column 64 
Banjiliar Scieijce. 
THE MAGIC CASH BOX. 
A CURIOUS little toy is illustrated in 
Aa Nature, called the Magic Cash Box. 
Viewed from the front through the glass 
forming one of its sides (A), it appears to 
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The Magic Cash Box. — A, Front view through g:lass side. 
B, Rear view with back removed, showing arrangement of 
mirrors. 
be simply an empty box, covered on the 
interior with white cloth or paper. Now, if 
a coin is dropped into it through the slit in 
the top, it immediately vanishes, the box is 
apparently as empty as before, and the ques- 
tion printed at the back, Ou est passe la 
monnaie? (Where has the money gone.?) 
becomes a very pertinent one. 
The mystery is solved by removing the 
back of the box (B) and examining the 
interior. We then find that the box is not 
really empty, but contains two mirrors, 
placed together at an angle of 45°, with the 
apex of the angle facing the front of the box. 
These mirrors reflect the sides of the box, 
and produce the illusion that one is looking 
directly at the back, when, in reality, it is 
the reflection of the sides that we see, and the 
money dropped into the box is concealed in 
the space behind the mirrors. 
This ingenious toy can easily be made by 
anyone with two pieces of looking-glass cut 
to the proper size. Care must be taken to 
have the cloth or paper covering the inside of 
the box perfectly white and clean, with no 
marks or figures to be reflected. The mir- 
rors must be placed . at an angle of exactly 
45°, and the edge where they come together 
is concealed by a narrow strip of card bearing 
the legend noted above. 
[Original in Popular Science Jlew».\ 
LEAF MOSAICS. 
BY FRED'K LEROY SARGENT. 
Since the time when the illustrious Dr. Priestly, 
a little over a hundred years ago, discovered that the 
green parts of plants have the power of making 
the air around them fit for animals to breathe, 
the attention of the curious in such matters has 
Fig. I. Plantain-leaved Everlasting. (Original.) 
been repeatedly directed to the study of how the 
leafy shoots perform their work. It was early seen 
that sunlight is necessary to enable the leaves to 
drink in the carbon-laden particles from the air, 
and liberate from their confinement the atoms of 
oxygen ; and, after a while, it came to be understood 
that the purpose of this subtle activity was the mak- 
ing of nourishment for the plant. Once arrived 
Fig. 2. Water-starwort. (Original.) 
at the conception of foliage leaves as so many 
food-mills run by sunbeam-power, the great variety 
of form and arrangement, and the many peculiari- 
ties of behavior exhibited by leaves, acquired a 
new interest from the hope thus given that an ex- 
planation of their queer ways might now be found 
by the use of this new key. 
One of the most brilliant results of the studies in 
this direction was the discovery that the arrange- 
ment of leaves on upright stems is governed by 
Fig. 3. Star-flower. (Original.) 
curious mathematical laws, according to which the 
place of origin of each leaf and the angle between 
successive leaves is fixed with remarkable precision. 
