SECTIONAL TRANSACTIONS.—A. 869 
and whim of an old Roman Emperor, absolutely prohibits orderly and rational 
summaries of statistical data in suitable units of conveniently increasing time. 
Let us promote the adoption of the simple equal-month calendar many others 
are now advocating, and thus make it easy, for all future time at least, to 
summarise data in units of weeks, fortnights, four-week months, thirteen-week 
uarters, and years of fifty-two exact weeks. It is an easy matter to absorb 
the unavoidable extra day in common years and the two such extra days in 
leap years. 
Publication of detailed data in extenso is generally prohibitive because of 
the enormous mass available, and because investigators cannot undertake the 
huge task of making the necessary summaries. It is hoped and recommended 
that the meteorologists may set a good example to scientists dealing with great 
bodies of statistical data, by helping to secure calendar simplification, and to 
agree upon some standard superficial units of continental areas for which 
summaries of standard and representative data should be published. 
These ideas have reference very largely to starting a system at the present 
time that will bring great benefits to future generations and posterity. To 
reap these same benefits ourselves we must wipe out the awkward summaries of 
back data we now use, and compute new summaries on the simplified-calendar 
basis. It will suffice if this be done for simply the major meteorological elements, 
and when we recall that the task might easily be apportioned among the many 
thousands of observers constantly on duty, the desired result can easily be 
attained. 
Tuesday, August 12. 
33. Prof. R. W. Woop, For. Mem. R.S.—Controlled Orbital Trans- 
fers of Electrons in Optically Excited Mercury Atoms. 
Mercury vapour at room temperature is illuminated by radiation of wave- 
length 2536 in combination with monochromatic radiation of one or more other 
wave-lengths corresponding to are lines of mercury. In this way electrons, 
brought to the 2p. orbit by the absorption of 2536, can be carried to one or 
_ more known outlying orbits, and certain of the mercury arc lines are radiated 
_ and can be photographed. From intensity measurements of the lines statistically 
_ data can be directly obtained regarding the probability of certain orbital 
transfers. 
Most remarkable of all is the effect of additions of small traces of nitrogen 
to the mercury vapour. This caused a powerful emission of the so-called water- 
band in the ultra-violet, a thirty-fold increase in the intensity of emitted green 
radiation (2536), and the introduction of an absorbing power for the violet 
; line 4046 (which is not absorbed by the excited vapour in vacuo) so great that 
_ the line is practically suppressed when the light of the arc is passed through a 
; layer of vapour 5 cm. in thickness. 
34. Discussion on The Scattering of Light. 
(a) Prof. C. V. Raman, F.R.S.—The Scattering of Light in 
Relation to the State of Molecular Aggregation. 
The paper summarises recent work carried out by the writer and his students 
with the aim of comprehensively studying the dependence of the light-scattering 
power of a substance on the state of aggregation of its molecules. Various 
theoretical questions which arise are also discussed. 
1. Experiments on the scattering of light by gases and gaseous mixtures 
at high pressures have been made (with Mr. L. A. Ramdas). Oxygen, carbon 
dioxide, and mixtures of these gases at pressures ranging from 1 to 150 atmo- 
spheres have been used. The variation of the scattering power under different 
conditions is best discussed with the aid of the thermodynamic surface repre- 
senting the properties of the mixture. 
_ 2. Light-scattering in liquids and in the corresponding vapours has been 
studied (with Mr. 8. Krishnan and Mr. A. S. Ganesan respectively). Some 
Seventy liquids, mostly organic compounds, have been investigated, and also 
the corresponding vapours as far as practicable. ‘lhe comparison between 
vapour and liquid furnishes a valuable test of theories of light-scattering. 
1924 BB 
