Notes. 
5 16 
[July, 
is that oxygen resides lower than the reversing layer. He had 
lately been extending the dispersion of the speCtrum of terres- 
trial oxygen, and from a light of maximum intensity of one- 
candle power had now got a dispersion of 80 inches from A to 0 . 
He exhibited two of the original negatives of the solar spec- 
trum, showing the bright lines. “ The Times ” gives some 
interesting particulars respecting the time and labour involved 
in this research. The bobbin of the Gramme machine revolves 
once for each spark used in obtaining the photographs of the 
air speCtrum. Each photograph requires 30,000 sparks, and the 
photographs obtained in the last three years have required no 
less lhan 20,000,000 sparks, so that the bobbin of the Gramme 
machine has revolved 20,000,000 times. Although the petroleum 
engine used for driving the machine consumes only a couple of 
drops of oil at each stroke, 150 gallons have been used up in 
three years. 
At the recent Soiree of the Royal Society several novelties of 
great scientific interest were exhibited. In the first room were 
exhibited Mr. Crookes’s Exhausted Tubes and Apparatus, illus- 
trating various phenomena connected with Molecular Physics in 
High Vacua. A description of these experiments will be found 
in the “ Monthly Journal of Science” for June. In another room 
Prof. Guthrie, F.R.S., exhibited Broken Glass in Frames, illus- 
trating the FraCture of Colloids. The working of the Writing 
Telegraph was shown by Mr. E. A. Cowper. The objeCt 
attained by this instrument is that it enables the operator to 
write at a distant station many miles away, just as though he 
were present there himself, without requiring the use of any 
special signals, codes, or signs (to spell each letter as is now the 
practice), and without the assistance of any person to translate 
the signals as received. The instrument aCts upon the simple 
principle of communicating at all times to the writing pen at the 
receiving end of the line, the exadt position of the pencil of the 
operator at the sending station through two line wires, or, so to 
speak, giving the latitude and longitude of the pencil continually, 
the position of the pencil vertically being communicated by one 
wire, and the position horizontally being communicated by the 
other wire. The pencil of the operator has two light “ contaCt 
rods ” jointed to it, and one of these slides over the edges of a 
series of “ contaCt plates,” having various resistances interposed 
between them and the line wire, while the other rod slides over a 
second set of such plates connected to the other line wire ; at the 
receiving end of the line each of these wires actuates its own 
needle. The two needles (which are placed at right angles to 
each other, and are provided with light springs) actuate one 
writing pen, so that the pen moves up or down, and backwards 
or forwards, in exaCt obedience to the motions of the pencil in 
the hand of the operator at the distant station. Both the paper 
written upon in pencil by the operator at the sending station and 
that written upon in ink by him at the receiving station move 
