June 30, 192 1] 



NATURE 



557 



Protective Measures against X-rays and Radium. 



A COMMITTEE was recently formed in 

 *^ London to see whether some general pre- 

 cautionary measures could be outlined which 

 would be of service to those employed in the use 

 of X-rays or radium for medical, scientific, or 

 industrial purposes. The members of the com- 

 mittee are as follows : Sir Humphry Rolleston 

 (chairman), Sir Archibald Reid, Dr. Robert Knox, 

 Dr. G. Harrison Orton, Dr. S. Gilbert Scott, 

 Dr. J. C. Mottram, Dr. G. W. C. Kaye, and 

 Mr. Cuthbert Andrews. Dr. Stanley Melville 

 and Prof. S. Russ are acting- as honorary secre- 

 taries to the committee. The need for a 

 statement on this subject has been felt for some 

 time. During the war the Rontgen Society issued 

 a printed card pointing out the dangers of expos- 

 ing parts of the body to X-rays unduly, but the 

 uses of these forms of radiation are becoming so 

 numerous in medicine and the arts that it was felt 

 that the ground should be gone over in more 

 detail, and general recommendations drawn up as 

 to the conditions under which work of this char- 

 acter should be carried out. 



The preliminary report of the committee has 

 just been issued. It is a carefully thought-out 

 statement of present knowledge in regard to the 

 equipment, ventilation, and working conditions of 

 X-ray and radium departments. We are glad 

 to see from the introduction to the report that 

 the committee holds the view that the dangers 

 which may attend the use of these radiations can 

 be avoided entirely by the provision of eflficient 

 protection and suitable working conditions. 



The damage which people have suffered in the 

 past falls into two categories : — 



(i) Visible injuries to the superficial tissues 

 which may result in permanent damage. 



(2) Derangements of internal organs and 

 changes in the blood. These are especially im- 

 portant, as their early manifestation is often un- 

 recognised. 



The protective measures to be employed natur- 

 ally vary with the work in hand, and the report 

 contains details of the measures which the com- 

 mittee thinks appropriate to (i) X-rays for diag- 

 nostic purposes, (2) X-rays for superficial therapy, 



{3) X-rays for deep therapy, {4) X-rays for in- 

 dustrial and research purposes, (5) electrical pre- 

 cautions in X-ray departments, (6) ventilation of 

 X-ray departments, and (7) radium therapy. 



The report concludes with a statement bearing 

 upon several aspects of the subject, and we ac- 

 cordingly reproduce it in full : 



"The governing bodies of many institutions 

 where radiological work is carried on may wish 

 to have further guarantees of the general safety 

 of the conditions under which their personnel 

 work. 



"(i) Although the committee believe that an 

 adequate degree of safety would result if the 

 recommendations now put forward were acted 

 upon, they would point out that this is entirely 

 dependent upon the loyal co-operation of the per- 

 sonnel in following the precautionary measures 

 outlined for their benefit. 



" (2) The committee would also point out that 

 the National Physical Laboratory, Teddington, is 

 prepared to carry out exact measurements upon 

 X-ray protective materials, and to arrange for 

 periodic inspection of existing installations on the 

 lines of the present recommendations. 



"(3) Further, in view of the varying suscepti- 

 bilities of workers to radiation, the committee 

 recommend that wherever possible periodic tests 

 - — e.g. every three months — be made upon the 

 blood of the personnel, so that any changes which 

 occur may be recognised at an early stage. In 

 the present state of our knowledge it is difficult 

 to decide when small variations from the normal 

 blood-count become significant." 



It is satisfactory to learn that the committee 

 intends to continue to meet and to consider the 

 advisability of directing some researches which 

 arise out of the considerations involved in the 

 memorandum in question. 



Suggestions and offers of personal or other 

 assistance are invited ; they should be forwarded 

 to the honorary secretaries of the X-ray and 

 Radium Protection Committee, from whom copies 

 of the preliminary report may be obtained, c/o 

 Royal Society of Medicine, Wimpole Street, W. i. 



Cosmogony and Stellar Evolution.^ 

 By J. H. Jeans, Sec.R.S. 



I. — The Evolution 0/ Gaseous Masses. 

 ' I ""HE progress of observational astronomy has 

 -*■ made it abundantly clear that astronomical 

 formations fall into well-defined classes ; they are 

 almost " manufactured articles " in the sense in 

 which Clerk Maxwell applied the phrase to atoms. 

 Just as atoms of hydrogen or calcium are be- 

 lieved to be of similar structure no matter where 

 they are found, so star-clusters, spiral nebulae, 

 binary stars are seen to be similar, although in 



1 Lectures delivered at King's Col'ege on May 3 and to. 



NO. 2696, VOL. 107] 



a less degree, no matter in what part of the sky 

 they appear. The problem of cosmogony is to 

 investigate the origins of these comparatively 

 uniform formations and the process of transition 

 from one class to another. 



In attacking this problem the cosmogonist of 

 to-day stands upon the shoulders not only of 

 previous cosmogonists, but also, what is of even 

 greater importance, upon the shoulders of the 

 brilliant and industrious astronomical observers 

 of the past century. We shall find it convenient 



