SECTIONAL TRANSACTIONS.—A. 331 
Mr. J. H. AwBery and Dr. Ezer Grirritus, F.R.S.—Humidity Measure- 
ments at Temperatures from 40° C. to 100° C. 
The subject of humidity measurement and control is rapidly assuming importance 
in many industries and, whilst existing tables are adequate for many purposes, they 
are not sufficiently extensive in range for some processes, such as timber drying. 
The methods available for measuring humidity above 40°C. are the dew-point 
method, the wet and dry bulb hygrometer, and the gravimetric method in which 
the moisture is absorbed from the air and measured by weighing. Of these the dew- 
point method is often very troublesome in hot atmospheres, and the gravimetric 
method suffers from the disadvantages that the results are averages over a period of 
time, and are not available until some time after the observations have been taken. 
Thus, in most cases, the wet and dry bulb method would be the most useful, if reliable 
tables were available over the whole range ; in consequence, experiments have been 
carried out to compile a set of tables for this instrument, covering the range 40° to 
100°C. dry bulb. 
In these experiments, the wet and dry bulb instrument was compared with both 
the types mentioned above. They give absolute results, and in general excellent 
agreement between them was obtained, so that the true humidity at each observed 
value for the wet and dry bulb instrument may be taken as known accurately. 
The observations have been reduced graphically to tabular form. 
Sir Narrer Suaw, F.R.S.—Meteorology after the Century. 
1. The development of the physical aspect. 
Reports, by a professor of natural philosophy, to the second meeting of the Associa- 
tion on the state of knowledge, deriding the ordinary meteorological practice, extolling 
the contributions of dynamics and physics and concluding, in a report to the tenth 
meeting, with an excellent account of meteorological optics. 
The contributions of distinguished physicists, Daniell, Regnault, Mascart, and the 
radiologists ; Stefan’s law. 
A professor of mineralogy’s gift of a place among the inductive sciences to mineral- 
ogy (in the history of inductive sciences) as the analytico-classificatory science— 
refused to meteorology because it was in fact the application of other recognised 
sciences to the atmosphere. 
2. The development of the geographical aspect culminating in the introduction 
of the weather-map with forecasts and storm-warnings. 
3. Sir F. Galton’s endeavour, as General Secretary of the Association in 1865, to 
combine the physical and geographical aspects in the solution of the problem of 
weather. The principles of weather-sequence as set out by R. Abercromby. The 
dominance of sea-level pressure-distribution. 
4, Sir Arthur Schuster’s appeal to the seventy-first meeting, for the deliberate 
co-ordination of meteorological observations for definite scientific purposes, and for 
the specification of the probability of inferences. 
5. The extension of knowledge by the exploration of the upper air in respect of 
pressure and motion, heat, water-vapour, light and sound. 
6. The uncertainties of forecasting. The reconsideration of the principles of 
weather-sequence by the Norwegian school and otherwise. 
7. The distribution of entropy, acting through gravity, and of kinetic energy, with 
the aid of the conservation of angular momentum, as the controlling factors of weather. 
Mr, C. Carus-Witson.—Demonstration on Musical Sands. 
Musical sands of sea-beaches and those of inland aeolian accumulations. Some 
notable examples. 
The conditions essential for the emission of musical notes from sand-grains. 
The production of musical sands artificially. 
The effect of various types of plunger and vessel upon the intensity of the sounds 
emitted. 
Conditions which render musical sands mute. 
The rhythmic acceleration of vibrations following abrupt frictional retardation. 
