A.— MATHEMATICAL AND PHYSICAL SCIENCES 35 



direct or alternating current distribution in the earth's surface, or the 

 impHed electromagnetic eflfects just above the surface, the details of the 

 methods employed were shrouded in mystery. 1° The report of the survey 

 has lifted the veil, and the aims of the Committee of Civil Research, in 

 suggesting this systematic research in the field, have been to a large extent 

 realised. We find the various methods fully described, some of them 

 having been devised and applied for the first time during the survey. 

 The difficulties and limitations, as well as the successes, are made plain, 

 and the conditions determining the choice of the most suitable methods 

 for particular problems are indicated clearly. It is, I think, no exaggera- 

 tion to say that the report is the most comprehensive and authoritative 

 treatment available of the subject of electrical surveying. 



The Future of Geophysical Surveying. 



Much, however, remains to be done in all branches of geophysical 

 surv'eying, in order to put it on a more secure basis and to determine more 

 certainly the scope of its applications. It must be confessed that until 

 quite recently practically all the work was being done by German investi- 

 gators, both in the construction and improvements of instruments, and 

 in their use in the field. But some interest has now been awakened in 

 this country, and considerable progress has been made in enabling us 

 to take an increasingly active part in the investigations. It would be a 

 pity to let this interest and activity die — yet that is the danger. Unfortu- 

 nately, in scientific undertakings, whether national or commercial, we 

 have not yet adopted one of the fundamental principles of the family, 

 when the call is everywhere, as now, for economy. Not the full-grown 

 and robust, but the newly-born and undeveloped, first feels the pinch. 

 And, if the infant has a particularly large appetite, or needs special and 

 expensive nourishment, proper provision is more than ever likely to be 

 withheld. In such a situation geophysical surveying finds itself just now. 

 By its nature the work is necessarily costly. Except as regards some 

 aspects of the construction and improvements of instruments it cannot 

 be confined to a laboratory ; and, with the same limitation, it can rarely 

 be an individual effort. Effective research in the field implies adequate 

 scientific personnel, transport, labour and materials, in addition to the 

 instrumental equipment. If we are to make substantial progress in this 

 direction the expense must be faced. 



I recognise that it would be foolish, as well as useless, to press now for 

 the initiation of any costly schemes. But it is permissible to hope and 



'" The Report of the Sub-Committee of the Committee of Civil Research on 

 Geophysical Surveying (H.M. Stationery Office, 1927) contains this passage : 

 ' In particular, the electrical method has throughout been treated, by the com- 

 panies employing it, as a jealously-guarded secret trade process. In the result, 

 little information is available to the general scientific world regarding the methods 

 employed . . . the apparatus required, the field operations, or the interpretation 

 of results. We believe that ... a full disclosure of the scientific facts would 

 tend, more than anything else, to stimulate the natural development of this 

 method of geophysical surveying, by placing it on a scientific footing, similar 

 to that of the gravimetric method.' 



