304 



DISCOVERY 



much interesting information on the subject. London, 

 we learn, is in far better condition in this respect than 

 is Rochdale, and the condition of Rochdale might be 

 improved 30 per cent, if attention were paid to smoke- 

 suppression measures within the power of local authori- 

 ties. 



Much ingenuity has been shown in devising apparatus 

 to investigate atmospheric conditions. The air is 

 drawn through a narrow jet, after passing through a 

 damping chamber, and strikes against a microscope 

 slide made of glass. When air passes through such a 

 jet under pressure, and emerges on the other side, it 

 is cooled — a fact of which advantage is taken in the 

 manufacture of liquid air. The moisture which was 

 taken up in the damping chamber condenses like dew 

 on the particles of dust and smoke in the air, and 

 these particles stick to the microscope slide, where 

 they can be examined and analysed. 



In a fog there are about 20,000 particles of dust in 

 London air in every cubic centimetre ; in dry, sunny 

 weather by the seaside there are from 100 to 200. 

 The composition of these dust-particles varies greatly. 

 Oily matter, probably derived from tar, forms much 

 of the impurity, and since such tar derivatives are, 

 chemically speaking, very inert, they probably remain 

 as permanent stains wherever they rest. We meet 

 the same difficulty b\' many sea-coasts to-day, where 

 the thick oils discarded from marine engines cover the 

 pebbles with a sticky coat which time and tide seem 

 only to increase in stickiness. Sometimes the air-dust 

 is distincth' acid and, therefore, very destructive to 

 stone and injurious to the lungs. There is a great deal 

 of interesting reading in this little publication — rang- 

 ing from comments on the probable meal-times of the 

 inhabitants of Rochdale to the effect of industrial 

 conditions on the purity of the air, and we trust that 

 one result of the Committee's activities will be a 

 renewed effort to suppress, as far as is possible, the 

 undoubted evils of an impure atmosphere. Perhaps, 

 before this generation has passed away, the pepper- 

 and-salt moth may pay us the compliment of resuming 

 its old garment of bucolic but more attractive grey. 



II. Sunspots and Climate 



The Air Ministry can certainly not be accused of a 

 narrow outlook. \\'e owe it to its Meteorological 

 Office that the weather predictions, instead of pos- 

 sessing, as of old, the glorious uncertaint}' of cricket, 

 have achieved a reliability almost as great as that of 

 a billiards professional. The temperature of the upper 

 air enables the weather prophet to interpret many 

 signs which were formerly of uncertain import. But 

 their activities do not end there, for at the same time 

 as the appearance of their valuable report on Atmo- 

 spheric Pollution, they have published a pamphlet on 



Variations in the Levels of the Central African Lakes, 

 Victoria and Albert. These lakes, famous as the birth- 

 place of the Nile, famous also in the annals of explora- 

 tion and adventure, show a very strange harmony, it 

 appears, with the mysterious spots on the sun's face 

 which have been the subject of so much conjecture. 

 Tables are given which appear to show that when the 

 occurrence of spots on the sun's face is at a maximum, 

 the levels of these lakes are lowest, and vice versa. 

 This effect is attributed to the fact that the tempera- 

 ture in tropical lands is highest at " spot-maximum," 

 and hence the evaporation on the lakes is greatest. 

 Rainfall, of course, plays a large part in the determina- 

 tion of the level of the lakes ; but on occasions varia- 

 tions from the normal level have been noted to a 

 marked degree without any corresponding change in 

 the rainfall, and in these cases the association with 

 sun-spots is remarkable. These observations are of 

 great interest ; on the state of affairs in these central 

 lakes depends, to some extent at least, the prosperity 

 of Egypt, the success of the cotton crop, and. there- 

 fore, the conditions of the cotton industry in Lanca- 

 shire. 



Opinion is very keenly divided on the question of 

 the influence of sun-spots on climate. In a recent 

 number of Discovery there appeared a review of a 

 work which sought to uphold the view that they had 

 a great influence ' ; and certain correspondents made 

 it plain that their opinions were of an opposite nature. 

 This latest piece of information on the subject may 

 well be commended to their notice. 



Reviews of Books 



A SOLDIERS CONTRIBUTION TO MESOPOTAMIAN 

 ARCH.EOLOGV 



Babylonian Problems. Bv Lieut.-Colonel W. H. Lane, 

 Indian Army (retired). With an Introduction by 

 Professor S. L.\xgdon. With maps and illustra- 

 tions. (John Murrav, 21s.) 



" The principal scientific contribution of this book," 

 says Professor Langdon in his introduction, " consists 

 in new and dependable topographical information on the 

 region between Samarra and Tell-Abir. These new maps 

 and the description of the region given in the text consti- 

 tute the best topographical information which has ever 

 been placed at the disposal of scholars." He adds that 

 the book " will never out-live its scientific value." Praise 

 such as this from so eminent and critical a scholar as 

 Professor Langdon leaves a reviewer with but little to 

 say. 



The chief problem with which Colonel Lane is concerned, 

 and around which to a great extent centre the investiga- 



1 Sunspots and Climate, by Dr. A. S. Russell. Discovery, 

 March 1923. 



