Vol. XXIV. No. 8.] 
POPULAR SCIENCE NEWS. 
125 
The Constellations. — The positions given hold 
good for latitudes differing not many degrees from 
40° north, and for lo, 9, and 8 P. M. for the begin- 
ning, middle, and end of the month, respectively. 
Lyra is in the zenith, Aquila is coming to the merid- 
ian at about 60 ' altitude, and Sagittarius is low 
down on the south meridian. East of Sagittarius is 
Capricornus, at about the same altitude, with Piscis 
Australis just rising below it. Aquarius follows 
Capricornus, and Pisces is just rising in the east. 
Above Pisces are Pegasus and Cygnus, the latter 
near the zenith. Going from the eastern horizon 
toward the pole star, we find first Andromeda, and 
next Cassiopeia. Perseus is on the horizon below 
Cassiopeia, and Cepheus is above. The head 
of Draco is just west of the meridian, and a little 
north of the zenith. Ursa Minor is mainly to the 
left and above the pole, while Ursa Major is to the 
left below. Hercules is to the west of the zenith, 
high up, and below it are Corona Borealis and 
Bootes, with Virgo just on the west horizon. Libra 
and Scorpius follow Virgo, and are both low down 
in the western sky. Ophiuchus is above Scorpius. 
M. 
Lake Forest, III., July 3, 1S90. 
QUESTIONS AND ANSWERS. 
Letters of inquiry should enclose a two-cent 
stamp, as well as the name and address of the 
writer, which will not be published. 
Questions regarding the treatment of diseases 
cannot be answered in this column. 
N. T., Tndia — If two wheels of different sizes are 
connected by a belt- or gearing, how may their 
relative speeds be determined? 
Answer- — The speed of such wheels is directly 
proportional to their circumferences. Thus if the 
driving wheel is twice the circumference of the 
driven one, the latter will turn twice as fast. If, on 
the contrary, the driven wheel is twice the circum- 
ference of the driver, the former will turn only 
half as fast as the latter. In all such cases, an 
increase of speed is accompanied by a loss of power, 
and vice versa. 
Builder, A'ew York. — What chemical changes 
take place in the drying and hardening of ordinary 
mortar .' 
Answer. — Mortar is usually composed of one part 
of slaked lime fcalcic hydrate) and two or three 
parts of sand. The hardening appears to he due, 
first to the absorption of carbonic acid from the air, 
by which a portion of the lime is converted into 
carbonate, and this uniting with the unaltered calcic 
hydrate forms a solid layer, adhering strongly to 
the surfaces of brick or stone. In the course 
of time, Ihe lime uniting with the sand forms a 
calcic silicate, which renders the adhesion even 
stronger and more perfect. 
H. T. H., Boston. — How can I make platinic 
hydrate from platinum scrap? 
Answer. — Dissolve the platinum in nitro-hydro- 
choloric Jicid, to form a solution of platinic chloride. 
Then boil the nearly neutral solution with potash, 
and treat the resulting precipitate with acetic acid. 
This leaves a nearly white powder of the composiion 
Pt(HO)4+2H20. At 100' C. this becomes Pt(HO)i. 
Unless you are accustomed to chemical manipulation 
you will find platinum a very difficult and unsatis- 
factory metal to experiment with. 
II. A. C, Illinois. — Will vines growing around a 
lightning rod injure its protective power? 
Answer — The presence of vines will make no 
difference whatever, and the rod will be equally 
efficient if it is entirely covered by the foliage. 
H. W. , iVass. — What can I use to remove lichens, 
etc., from an old gravestone? 
Answer. — A solution of caustic potash, or "con- 
centrated lye," will doubtless be effective. It will 
not injure the stone, but should be kept away from 
the hands or clothing as much as possible as it is a 
rather powerful caustic. 
C. D. N., Mass. — Does electricity exist upon the 
surfape of an electrified body, or through its entire 
mass ? 
Answer. — Static electricity, or electricity at rest, 
as in the case of a piece of glass or sealing wax 
electrified by friction, exists only on the surface 
of the body, but when a current of electricity passes 
through a conductor it traverses the whole mass, 
the conductive power of any two substances of simi- 
lar composition being proportional to their mass, or, 
in other words, their weight per linear foot. You 
will thus see that the shape of a lightning rod is 
of no consequence whatever, if it contains a 
sufficient weight of metal to carry off the current. 
C. A. G., Alabama — Qiiite a number of trains 
are now running which are lighted by electricity. 
The system is quite practical, the only objection 
being the great cost at which the electric lights are 
maintained in comparison with oil lamps. 
LITERARY NOTES. 
ffow to Examine for Life Insurance. Under this 
title. P. Blakiston, Son & Co., of Philadelphia, 
have published a book written by Dr. John M. Keat- 
ing, who is the president of the Association of Life 
Insurance Medical Directors, as well as the medical 
director of one of the large life insurance companies 
of the country. Dr. Keating's book might be pre- 
sumed to be, therefore, what its author says he 
intended it to be : a plain and practical manual for 
the life insurance examiner. Such it is, and as such 
it will prove a very useful companion for a class 
of men who are obliged to form an intelligent 
opinion upon an important matter in a brief space 
of time. 
n^ctliclne and Pljarnjacy. 
Advanced Physiography, by John Thornton, M. A. 
Longmans, Green & Co., New York. 
This work, which treats of the science of astron- 
omy as developed by the discoveries of modern 
times, is a most interesting and valuable treatise, 
and can be read with profit and pleasure by any- 
one having an acquaintance with the elementary 
principles of the science. The chapters on celestial 
spectroscopy are especially full, and include the 
results of the most recent investigations. 
The Disposal of ITousehold Wastes, by Wm. P. Ger- 
hard, C. E. D. Van Nostrand & Co., New York. 
Price, 50 cents. 
This work describes the best methods of disposing 
of the waste matters of houses in the country or 
small towns, where, as is often the case, there is an 
abundant supply of water, but no system of public 
sewers. This difficult problem is treated in a scien- 
tific and sensible manner, and the book will be 
found very helpful by those interested in the matter. 
Protoplasm and Life, by Charles F. Cox, is pub- 
lished by N. D. C. Hodges, of New York, at 75 
cents, and will be found an interesting and popular 
account of the tendencies of modern biological 
thought, including the views of the author on the 
theory of spontaneous generation, and its relation 
to the general theory of evolution. 
Philosophy in I/omrropathy , by Charles S. Mack, 
M. D., is published by Gross & Delbridge, of Chi- 
cago, and is recommended to the perusal of those 
who wish to become better acquainted with the 
principles of that system of medicine, as held by a 
practical physician. 
The Open Court Publishing Co., of Chicago, 
publish .1 collection of very dreary essays (price, 
$[.oo) upon labor and social questions, by a writer 
under the nom de plume of "Wheelbarrow." A 
few of these essays are sensible, the majority are 
supremely nonsensical, and none show the slightest 
trace of any original or independent thought. 
The Engineers' and Contractors' Diary and Refer- 
ence Hook, published by E. & F. N. Spon, New 
York, at 50 cents, contains many useful tables, and 
interesting information especially adapted to the 
use of civil engineers. It also contains blank spaces 
for memoranda, etc., for every day in the year. 
Pamphlets, etc., received: An Imprcved Tape- 
Measure, by William C. Krauss, M. D., Buffalo; 
Report of the Intercollegiate Committee of the Ameri- 
can Institute of Ilomcpopathy; Catalogue of Pratt 
Institute, Brooklyn, N. Y. ; and the Circulars of the 
National Bureaus of Statistics and Education. 
AUTOGRAPH ISM. 
Under this name Dr. Mes.net has recently 
described to the Paris Academy of Medicine, 
a curious disease, or condition, of certain 
patients of liis, which manifests itself in a 
remarkable sensitiveness of the skin to 
pressine or friction. 
Dr.-Mesnet finds that when the skin of such 
a person is written upon with a pointed instru- 
ment, pressed witli the fingers, or even rubbed 
by a fold of the clothing, a very curious set 
of piienomena occur. In the first place a 
slight redness of the skin appears at the 
points where pressure is applied, or follows 
the point of the instrument forming the letters 
or figures. In about two minutes the cliar- 
acters appear in lines of a pale red color and 
increase in height, iintil the inscription stands 
out on the skin of the patient in red letters 
of bold relief. The characters remain visi- 
ble for a considerable time, varying, with 
different jybjects, from a few minutes to 
several hours, after whicli the skin resmnes 
its normal appearance. The accompanying 
engraving is copied from La JVaiurc, and is 
a reproduction of a photograph of a subject 
upon whom the phenomenon was produced 
for the express benefit of our contemporary. 
While Dr. Mesnet is unable to find a satis- 
factory explanation of this phenomenon, he 
considers it as due to a disordered condition 
of the nervous system, of a hysterical nature, 
affecting the circulation of the blood-vessels 
of the skin. Nearly all the patients showing 
this autographism had various other nervous 
affections, and were easily affected by liyp- 
notic influences. Local anassthetization of the 
skin by ether spray temporarily prevented 
the occurrence of the phenomenon, but it 
reappeared as soon as the effects of the ether 
passed away. This effect would naturally 
result, for in this form of local anaesthesia the 
