Commission 12. (Solar Radiation and Solar Spectroscopy.)

The Chairman referred with sorrow to the loss of Dr St John, the former President of the Commission, who died a few months before the meeting.Solar radiation. The President suggested and Prof. Chapman agreed that it would be interesting to make investigations at high altitudes, especially at wave-lengths of about 2100 A.Solar Spectroscopy. Prof. Russell said that the publication of new tables of the infra red solar spectrum would be delayed by the illnesses of Miss Moore and of Dr Babcock.</jats:p

12. Commission de la Radiation Solaire et de la Spectroscopie Solaire

The majority of the members of the Commission have been good enough to send in full reports regarding subjects of interest to this Commission. Extracts from them relating to questions which may be the subject of useful discussion at the forthcoming meeting in Paris are given below; references to research undertaken during the last three years, particulars of which are readily available in recent astronomical publications, are omitted.</jats:p

13. Commission des Éclipses Solaires

(i) 1936, June 19. The Eclipse Committees of Japan and the U.S.S.R. have been making preliminary meteorological studies of the weather conditions along the belt of totality in their respective countries. The Japanese Committee report (Bulldin, Kwasan Observatory, 283, 1934) that, while at the extreme east and west of their totality zone the weather prospects are unfavourable, for the central part, along the north-east coast of the island of Hokkaido, from Esasi to Monpetu and in a region round Syari the weather conditions are as good as in the best seasons of Tokyo and Kyoto in an ordinary year. A pamphlet giving all information is being prepared and will shortly be circulated in astronomical circles, but it may be mentioned that Monpetu and Syari are accessible by rail from the port of Otaru. There is electric current, 100 V, A.c., labour is readily available and accommodation will be possible for small parties.</jats:p

36. Commission de la Spectrophotométrie

The present report is the first for which this newly-formed Commission has been responsible. In view of this fact, and in view of the still exploratory nature of many investigations in spectrophotometry, as well as the need for the highest measure of individuality in the attack of the not simple problems involved, it would be premature to propose, simple though it might be to do so, any far reaching plans for co-operative schemes of investigation. These undoubtedly will play a part in the later work of the Commission, but what appears to be needed now is a closer definition of the aims of spectrophotometry, and at least a reference to the many branches of the subject where investigation is needed. The present report attempts to deal with these topics in three successive sections, concerned in turn with the unique property of spectrophotometric measures, the fields of application of spectrophotometry, and recent developments in a still incomplete and difficult technique.</jats:p

12. Commission de la Radiation Solaire et de la Spectroscopic Solaire

The Commission has suffered the heavy loss of Prof. W. Bernheimer, who was co-opted on to our Commission and whose work is well known and appreciated.The following report touches the subjects of interest to this Commission as treated by the various members and is not an account more or less complete of the work done in them in the three years.</jats:p

36. Commission de la Spectrophotométrie

At the first meeting of the newly formed Commission on Spectrophotometry, at Paris in 1935, a thorough discussion, aided by several reports, took place on the principles of this branch of astrophysics. So it will be sufficient now to treat only such special points of theory and practice as have won interest by researches of the last few years.</jats:p

13. Commission des Éclipses de Soleil

Since the date of the 1935 Paris meeting two total eclipses have been successfully observed. Throughout the long path crossing Siberia and Japan the weather on June 19, 1936 on the whole about lived up to predictions. On account of widely scattered clouds neighbouring expeditions had quite different luck with the weather. In contrast, the June 8, 1937 eclipse was seen throughout the whole track under universally clear skies, which is all the more surprising for the reason that eclipse expeditions to the tropics usually fare badly with the weather. Stewart and Stokley in a ship at sea were able to observe the eclipse with a measured duration of 7 min. 6 sec., the longest period of totality in 1200 years.</jats:p

12. Commission de Physique Solaire

The president calls attention to the large and increasing membership of Commission 12 and the policy of concentrating in it all matters relating to the sun. The result makes it comparable in breadth of field and in membership to the former Union for Co-operation in Solar Research. The main point in favour of this policy is the increased interest in the meetings of the Commission and the larger number of individuals reached compared with the meetings of small committees. One recalls the general sessions of the Solar Union in which each one present felt himself a part of the Union and in real touch with the work of different sections and after the discussions went away with fuller knowledge of what it was all about. This was a valuable result not attained to the same degree from the general sessions of the present Union, but in a measure it does follow from the meetings of the Solar Physics Committee. On the other hand the question may be raised whether or not the merging of independent commissions into subdivisions of a large commission lessens their interest to an extent not balanced by the advantages. If the present policy holds, it seems to the president that a re-organisation of Commission 12 is advisable by which more responsibility is laid upon the directors of centres. The basis of membership in the Commission may well be considered and recommendations formulated for transmission to the Executive Committee.</jats:p