THE MEDITERRANEAN NATURALIST 407 
the instrument useless at low temperature; 
and the alcohol thermometer is unreliable 
on account of the frequent evaporation of 
a portion of the fluid, which collects at 
the upper end of the tube. Sulphuric acid 
gives off no vapor at atmospheric tempe- 
ratures, expands in the tube with perfect 
uniformity, and freezes only when the 
temperature falls to 112 below zero. 
Photographs of the sky, including aii 
stars down to the fourteenth magnitude, 
are now being made at IS places — Paris, 
Bordeaux, Toulouse, Algiers, Greenwich 
Rome, Catania, Helsingfors, Potsdam. Ox- 
ford, San Fernando, Tacubaya, Santiago, 
La Plata, Rio Janeiro, the Cape, Sydney, 
and Melbourne. 
Varying evaporation and influx of 
composition and density in different parts 
cause the sea to vary greatly in compo- 
sition and density in different parts. A 
late Russian map shows that the center 
of maximum salinity in the Pacific lies be- 
tween 20° and 30° north latitude and at 
about 170° west longitude. A tongue of 
considerably fresher surface water stretches 
<u 
nearly across the ocean in about 10° north 
latitude, and sweeps round the coast of 
America and Asia, including the Behring 
Sea but not the Sea of Okhotsk. 
An extraordinary snowballing was expe- 
rienced at Glashutte, Saxony, on December 
4 last. Dr. Puul Schreiber states that the 
bails of snow, which were light and mea- 
sured from four to five inches, fell during a 
sudden calm in the midst of what seemed to 
be a thunderstorm The balls, five to twelve 
to a square yard, lay on the ground until 
the next day. 
!?P _ 
1 HE Simplon tunnel from Brieg in Swit- 
zerland to Ifella in Italy, will be 12.1 miles 
long. 
SoME years ago a Belgian chemist com- 
pressed metallic powder until the particles 
coalesced and formed a solid ingot, thus gi- 
ving an effect ordinarily due to heat. An 
English chemist, Mr. H.N. Warren, belie- 
ves that he has now produced the chemi- 
cal combination of hydrogen and oxygen ; 
gases — which usually unite only on the ap- 
plication of heat — by simple pressure exer- 
ted at ordinary temperatures. In a small 
glass tube, into which were fused two pla- 
tinum wires, was hermetically sealed a cu- 
bic centimeter of acidulated water. An elec 
trie current of six volts was applied, and 
the water was rapidly decomposed into hy- 
drogen and oxygen until the end of 25 mi- 
nutes, when the pressure of the gasses is 
supposed to have reached about 5700 pounds 
to the square inch, there 'was a vivid flash 
succeeded by a violent report, the glass being 
shattered and its fragments scattered with 
great force. The explosion gave sufficient 
evidence of the union of the gases, and im- 
mersion of the tube in cold water had made 
heating improbable. 
The two most widely accepted explana- 
tions of the maintenance of solar heat 
are (1) that it is due to the energy developed 
by meteoric matter falling on the sun. and 
(2) that it is produced and kept up by slow 
contractions of the sun’s bulk. Considering 
these hypotheses, Dr. Joseph Morrison, of 
the American Nautical Almanac office, has 
