May 30, 19 1 8] 



NATURE 



247 



ihis it is necessary to reduce the local observed 

 value to sea-level. This involves an estimation of 

 the masses of the earth above sea-level, both 

 above and below station-level, in order that their 

 effect may be correctly allowed for. 



Mr. Oldham first takes the case of an imaginary 

 mountain range agreeing approximately m its 

 dimensions with the Himalayas, but more regular 

 in form, consisting of a plateau of 15,000 ft. alti- 

 tude, from which an inchne of 100 miles in 

 breadth descends to 5000 ft. by a series of steps, 

 and terminates in another plateau at an altitude 

 of 1500 ft., and 20 miles broad, bounding the 

 liangetic trough on the north. 



Utilising this imaginary range, the effects of 

 various hypotheses of compensation are con- 

 sidered, and the deflections at a series of points 

 on a line crossing the range are computed and 

 tabulated. The attractions .of the visible masses, 

 both compensated and uncompensated, are com- 

 pared, and also the topography of the imaginary 

 range and the actual topography, as determined 

 by Major Crosthwaite, R.E. The Siwalik Hills, 

 with their lower density of about 2'2, as com- 

 pared with the 2-7 of the Himalayas, are separ- 

 ately taken into account. The case of uniform 

 compensation to different depths is examined and 

 compared with the results given on the assump- 

 tion of a variable compensation. 



Passing from the hill range to the Gangetic 

 trough, reasons are given for taking the value 

 2' 16 for the density of its filling material, and on 

 this assumption the deflections due to such a 

 trough of various depths, breadths, and sectional 

 forms are computed and compared. All this forms 

 a standard of comparison for estimating the value 

 of the observational material, and the geodetic 

 data along lines traversing the Gangetic trough 

 are next examined, the conclusion being reached 

 that the maximum depth of the trough need not 

 exceed 25,000 ft., and can scarcely be less than 

 20,000 ft., according to the deflection observa- 

 tions. The gravity observations are next dis- 

 cussed and are considered to bear out generally 

 the conclusions which had been reached on the 

 deflection data and to indicate a general upward 

 slope of the floor of the Gangetic trough towards 

 the south. Special cases at Dehra Dun, in the 

 Punjab, etc., are discussed in fuller detail, and 

 near the Siwalik Hills a maximum depth of at 

 least 10,000 ft. for the trough is highly probable. 



The next stage in the investigation is a dis- 

 cussion of the support of the Himalayas, and 

 taking the Himalayan geodetic stations, the prob- 

 able and actual deflections are cx)mpared. Local 

 topographical irregularities introduce difficulties 

 in some cases, but there is in all three regions 

 examined an excess of observed over calculated 

 deflection in a northerly direction. Neither altera- 

 tion in the depth to which compensation extends 

 nor the adoption of a hypothesis of flotation pro- 

 vides an explanation, but the author would attri- 

 bute it to departures from locally complete com- 

 pensation. The observations of M. de Filippi's 

 expedition to the Himalayan region should add 

 NO. 2535, VOL. lOl] 



valuable material for this inquiry, but at present 

 there seems to be a defect of gravity as the hills 

 are entered. 



This memoir is a valuable addition to geo- 

 physical literature, and a useful contribution to 

 the study of a difficult problem which will be wel- 

 come'd both by geologists and geodesists. It is to 

 be regretted that the illustrations are poor speci- 

 mens of such work, for there should be no diffi- 

 culty in providing more satisfactory blocks. The 

 omission of an indication of the units employed 

 in several of the tables is tiresome to the reader. 



H. G. L. 



CLIMATOLOGY AND AN ABANDONED 



FLYING SCHOOL. 



'X'HE Times of May 20 contains a summary of 



-■- the third report of the Select Committee on 

 National Expenditure, which gives the material 

 facts about the abortive scheme of the War Oflfice 

 to establish at Loch Doon, Ayrshire, a large 

 school for the training of airmen in gunnery. It 

 is a striking and very expensive example of that 

 incoherence or lack of co-ordination under stress 

 against which the discipline of science as a part 

 of education should be our safeguard. In 1916 

 the Air Board wanted an aerodrome for special 

 purposes, and found a site at Loch Doon which 

 would fulfil their requirements provided that a 

 peat-bog on the western side of the lake could 

 be drained and certain engineering work carried 

 out on the eastern side. Taken independently, 

 both these conditions could be satisfied, and 

 operations were set on foot. By May, 1917, the 

 estimated cost was 350,000!. ; afterwards, large 

 further sums were being asked for to complete 

 the scheme ; but, though each item had been 

 separately satisfied, the object was not achieved. 

 The climatic conditions were quite unsuitable for 

 a training school, the local "bumps" were a 

 great drawback for the special purpose of the 

 aerodrome, the conditions of the surrounding area 

 placed intolerable restrictions upon its use, and, 

 on account of the increased speed of flight, the 

 engineering works were already out of date. In 

 January, 1918, the Air Council decided to cut the 

 loss and abandon the scheme. 



Looking back at the evolution of this fiasco, 

 various points are .evident. The air authorities 

 apparently worked by the map, the engineers con- 

 sidered only the questions of draining a bog and 

 constructing certain railways, hangars, etc., not 

 the making of an aerodrome ; and the vexatious 

 details of the climate of the British Isles were 

 left to express themselves in their own inexorable 

 way when the mechanical operations had been 

 provided for. The last is, p>erhaps, the most in- 

 structive feature of the situation.. Climatology is 

 the science which uses the common experience of 

 past weather to safeguard the future of all opera- 

 tions that depend upon weather. Its basis of fact 

 is merely organised public memory. The Meteoro- 

 logical Committee, in its reports, has frequently 

 urged that, in the public interest, local authorities 



