SOUND. VIBRATIONS PHOTOGRAPHED. 475 
and one-half miles, snow does not melt; that century after century "eternal " 
-snow whitens lofty peaks in all latitudes. 
The temperature of a place on the earth's surface depends on many influ- 
ences, any one or several of which may be greatly modified or annulled by the 
others; so that there is no general rule for climate. 
As a part of the multitude of things to be taken into consideration as touch- 
ing the matter in hand, we may name these, viz: The latitude, the . elevation 
above the sea-level, the ocean currents, the direction of the prevailing winds, the 
presence and trend of mountain ranges, the amount of vapor usual in the atmos- 
phere, the degree of cloudiness, the quantity of rain and snow-fall, the size of 
the body of land, the amount of land in close proximity and its surroundings, 
the nature of the soil, the amount and kind of vegetation, the density and height 
■of the atmosphere, the length of the day, the obliquity of the Sun's rays, and 
the thousand and and one other things which go to make up the whole tempera- 
ture and climate. Of the greater part of these — indeed, of almost every one of 
them — as exhibited on other planets, it is absolutely impossible to know any- 
thing at all, and as a matter of course, no one can speak intelligently of the 
climate on any planet except our own. But should all these items be known, 
the further question arises whether it is not possible that animated beings could 
live in an environment totally unlike that which surrounds us. The conclusion 
of the whole matter, so far as astronomy and physics can now tell, is this : That 
the four large outer planets have not sufficiently cooled down to allow life on 
their surface, such as we see on the earth ; that Mars gives all telescopic and 
spectroscopic probabilities of conditions compatible with life as we see it; that 
the earth certainly for millions of years has been covered with multifarious life ; 
that of Venus and Mercury we have no certain knowledge; and that the satellites 
are pretty certainly not fitted for such life as is on the earth ; that, in particular, 
■our Moon has no water and no atmosphere, consequently no climate or vegetable 
life. If the Sun and the planets continually lose heat, then there will come a 
time in the far future when the Sun itself shall go out in etverlasting night, and 
the planets cool down so that the " eternal snow" would be hot compared with 
the degree of cold throughout all space where everything shall be dead. 
SOUND VIBRATIONS PHOTOGRAPHED. 
Photography appears to be running a race with electricity in curious develop- 
ments and novel appHcations. George G. Rockwood, the well-known photo- 
grapher, has just achieved the remarkable feat of photographing sound-waves 
instantaneously. The instrument by which the sound-wave was represented or 
(made visible in its effect is a new telephone, the inventor of which has obtained 
from Mr. Rockwood a perfect ocular demonstration of its vocal repeating action. 
The vibrating diaphragm, upon which the voice is projected, has a fine metallic 
point mounted on the center of its reverse side. This point meets the pointed 
