270 
POPULAR SCIENCE REVIEW. 
LIGHT. 
The analogy between the electric and sun light has been shown in a 
striking manner by Herve Mangon. It is well known that plants grown in 
darkness, or exposed only to artificial light, are deficient in their green colouring 
matter ; and it has always been considered that the sun’s light is essential to 
its development. Mangon has now proved that the green matter is equally 
capable of being produced under the influence of the electric light. Availing 
himself of a powerful magneto-electric light worked by a small steam-engine, 
he exposed several flower-pots, each containing four grains of rye, for about 
twelve hours a day during five days, to the rays of the lamp. The grains, 
when exposed, had just sprouted, but showed no appreciable green tips. 
They were placed about a yard from the charcoal points, and were carefully 
protected during the whole of the time from external light. On the fifth 
day the experiment was brought to an end, when it was found that all the 
plants were as perfectly developed as if they had been in the open air, and 
all exhibited their natural green colour, and were strongly inclined towards 
the light. Corresponding seeds, grown in darkness for the same time, grew 
up perfectly yellow. 
METEOROLOGY. 
“ On the Distribution of Aqueous Vapour in the Atmosphere,” is the title 
of a paper read before the Royal Society by Lieut.-Colonel Richard Strachey. 
In all our recent meteorological observations, it has been the practice to 
separate vapour pressure from the pressure of the dry air, under the impres- 
sion that the quantity of water vapour in the atmosphere influenced its 
pressure, as shown by the height of the barometric column. To determine the 
correctness of this practice, Colonel Strachey examines the hypothesis of Dr. 
Dalton, the observations of Dr. Hooker in the Eastern Himalaya, those of 
Mr. Welsh in his balloon ascents, and those by himself in Kumaon on the 
Himalaya, at heights varying from 1,000 to 19,000 feet above the sea-level. 
The quantity of vapour rapidly diminishes in the higher regions, consequently 
the ratios of the observed barometric pressures should be widely different 
at various elevations. This is not found to be the case. We must refer 
inquirers to the paper itself. Colonel Strachey’s conclusions are thus given : — 
“ Now, it follows, from an obvious mathematical law, that the entire quan- 
tities of vapour in these different cases are inversely proportional to the con- 
stant reduction of density ; so that the quantity on Dalton’s hypothesis, 
which is that represented by the observed tension at the surface, is to the 
quantity according to Dr. Hooker as sixteen to four, and to the quantity 
according to Mr. Welsh as eighteen to four — a result nearly identical with 
the former. The subtraction of the observed tension of vapour from the total 
barometrical pressure, in the hope of obtaining the single gaseous pressure, must 
consequently be denounced as an absurdity ; and the barometrical pressure thus 
corrected, as it is called, has no true meaning whatever .” 
The Winds. — Mr. James Glaisher, F.R.S., has just communicated to the 
Meteorological Society a paper on the duration of the winds in each month 
of the year. From 1841 to 1860, Mr. Glaisher obtains entirely reliable 
information ; before that time the observations were defective. 
