(596 
Proceedings of the Royal Society 
so to speak, been simply taking stock of the amount of the world’s 
capital invested in the heat of our atmosphere, and our investiga- 
tion shows us that we have been overestimating this quantity, and 
that the produce of the world is obtained by a less expenditure than 
we supposed. 
Monday, June 1884. 
EDWARD SAND, LL.D,, Vice-President, in the Chair. 
The following Communications were read ; — 
1. Abstract of Paper on Micrometrical Measures of Gaseous 
Spectra. By C. Piazzi Smyth. 
[Printed in full, with Plates, in tlie Transactions. ] 
Ever since the Royal Society, Edinburgh, was pleased to accept 
my paper in 1880, on the general appearance of Gaseous Spectra, 
as seen on a very small scale ; but complete on that scale from end 
to end of the visible spectrum, — I have been desirous of presenting 
them with some very highly-dispersed views of the more intricate 
portions of those spectra. 
An example in that direction was finely set by MM. Angstrom 
and Thalen in the Upsala Transactions in 1875. But though their 
work was splendid for its day, it is not enough to satisfy the 
demands of theory now. 
These demands, too, are so terribly exacting, that I have had to 
labour for several years at continual cumulative improvements of my 
private spectroscope, before it attained power and precision enough 
for the present work. This, however, is the comparative condition 
lately attained. 
My spectroscope of 1880 had a dispersion of 3°, with a magni- 
fying power on the telescope of 10 times ; say for the simple eye = 
30° from A to H. 
The Upsala instrument had a dispersion of 24°, with a magnifying 
power of about the same ; say = 600° from A to H. 
But my present spectroscope has 60° of dispersion ; a magnifying 
power on the telescope rising to 36 ; with a further mechanical 
magnifying of 5 times. Equal altogether to 9000° from A to II ; 
