2o6 



NA TURE 



[July 2, 1908 



tne vear 1904, compiled by Dr. Otto Baschin, and pub- 

 lished under the title of " Bibliotheca Geographica " by 

 Mr. W. H. Kuhl, of Berlin. The works are arranged 

 according to subjects included under the two main divisions 

 of general geography and special geography, the latter 

 being subdivided under headings dealing with different 

 countries. In the various subdivisions the works dealt 

 with are classified under the names of the authors, and 

 include publications in several languages. 



Is an article in the Cairo Scientific Journal for March 

 Captain H. G. Lyons, F.R.S., deals with " Some Unsolved 

 Problems of the Nile Basin." Exploration in this region 

 by geographical pioneers has extended our knowledge of 

 its main features, but detailed surveying is needed, 

 especially on the northern margin of the equatorial plateau 

 and of the Abyssinian tableland. In the field of geology 

 Captain Lyons gives a sketch of the history of the Nile 

 Valley, and comments on the secular rise of the lower 

 valley and its future effects on Middle Egypt. Observa- 

 tions are required of the underground water table, its 

 seasonal movement, and level with reference to the river. 

 No definite information can be obtained of the coal or 

 other minerals of commercial value until the early geo- 

 logical history of north-east Africa is better known. The 

 great meteorological problem to be solved is that of the 

 monsoon rains of Abyssinia and the Sudan. The develop- 

 ment of rains in equatorial regions, snowfall on the 

 Himalayas, and high-pressure conditions in North Africa 

 are some of the influences to be studied as possibly affect- 

 ing the Abyssinian rains. Historically, the question of the 

 change of climate in North Africa is of great interest, 

 although other causes should be considered simultaneously 

 in accounting for the decay of the flourishing settlements 

 which once existed in this region. Referring to the oases 

 of North Africa, Captain Lyons reviews briefly the evidence 

 of underground water in the desert, and states the problems 

 of its supply and connection with the Nile. 



.\ GOOD illustration of the power of the weapon which 

 the discovery of the Rontgen rays has placed in the hands 

 of the medical profession is afforded by an article entitled 

 " A Study of Constipation by Means of the X-rays," by 

 Dr. A. F. Hertz, of Guy's Hospital, which appears in the 

 June number of the Archives of the Rontgen Ray. After 

 a dose of a bismuth salt has been administered to a patient 

 it is possible to foljow by Rbntgen-ray photography the 

 passage of the food through the oesophagus, stomach, and 

 intestines, and thus determine the position, and in some 

 cases the nature, of any obstruction which may be present. 



The Physikalische Zeitschrift for June 15 contains a 

 translation of a paper by Mr. O. M. Corbino, of the L'ni- 

 versity of Messina, on an arrangement for producing 

 almost constant direct currents of high potential. It 

 consists of an induction coil capable of giving a spark of 

 a few centimetres the primary current of which is supplied 

 through a Wehnelt interruptor having a very small anode. 

 The secondary is connected to the terminals of a con- 

 denser of a few micro-farads capacity which has a resist- 

 ance of about 20,000 ohms in parallel with it. Between 

 one terminal of the coil and the corresponding terminal 

 of the condenser a spark gap of 2 mm. is inserted. In 

 these circumstances a direct current of about 30 milli- 

 amperes flows through the 20,000 ohms, and its magni- 

 tude seems to be little influenced by change of value ol 

 the resistance. 



We have received a copy of a new quarterly journal 

 published by the Institution of the Post Office Electrical 



NO. 2018, VOL. 78] 



Engineers, and entitled the Post Office Electriccu 

 Engineers' Journal. The new journal is chiefly devoted 

 to technical matters of interest to Post Office engineers, 

 the articles in the first number dealing with various tele- 

 graphic and telephonic subjects. Doubtless sufficient scope 

 exists for such a paper amongst the large staff engaged 

 at home and in the colonies, and if future numbers fulfil 

 the promise of the first, it should go a long way to pro- 

 mote the spirit of fellowship and feeling of common 

 interest which is one of the main reasons for its inception. 

 It is to be hoped the editors will not be led to step out- 

 side the legitimate limits of such a more or less private 

 journal by attempting to make it the receptacle for much 

 original research, and thus adding one more to the already 

 excessive number of journals which the electrical engineer 

 must consult. The lighter and social sides also find 

 adequate treatment in the present number, the contributions 

 being in both prose and verse. We wish the new publica- 

 tion all success. 



A WELL-KNOWN experiment in physics is to freeze water 

 by placing under the receiver of an air-pump some water 

 in a shallow dish supported above a large dish containing 

 sulphuric acid. Upon exhausting the receiver, evaporation 

 rapidly takes place and the vapour is absorbed by the acid, 

 with the result that the temperature of the water may be 

 reduced to freezing point. We have recently had an oppor- 

 tunity of seeing the Raplin Hand Ice Machine, made by 

 the Pulsometer Engineering Co., in which this principle 

 is put to commercial use. The apparatus consists of a 

 large bottle containing the sulphuric acid, and connected 

 with the air-pump and a carafe or an ice-mould by means 

 of pipes. A wheel turned by hand serves to actuate the 

 pump, which reduces the pressure and also rocks the acid- 

 container, so that the acid is splashed thoroughly and the 

 absorption of the vapour by it is thus facilitated. In three 

 or four minutes a carafe of ice-cold water can be pro- 

 duced, and a block of ice weighing about i lb. in twenty 

 minutes. Half a gallon of acid constitutes a complete 

 charge, and will serve to cool from fifty to one hundred 

 carafes of water to freezing. The machine provides an 

 interesting and handy means of reducing temperature by 

 rapid evaporation. 



The Select Committee of the House of Commons on 

 the question of proposed daylight saving legislation has 

 now completed its inquiry, and agreed upon its report. 

 The report is understood to be favourable to the principle 

 of the Bill introduced earlier in the session on the subject 

 by Mr. Robert Pearce. The committee is in favour of the 

 introduction of a Bill to achieve the object in view by an 

 alteration of clocks to the extent of one hour at 2 a.m. 

 on the third Sunday in April and by an hour's alteration in 

 the opposite direction on the morning of the third Sunday 

 in September. 



A VERY useful classified list of Smithsonian publications 

 available for distribution has been published by the Smith- 

 sonian Institution of Washington. The volumes and 

 pamphlets are arranged conveniently according to subjects. 

 Applicants for these publications must state the ground of 

 their requests, as the institution is able to supply papers 

 only as an aid to the research or study in which the 

 applicant is especially interested. The volumes of contribu- 

 tions and of miscellaneous collections are distributed only 

 to public libraries and to learned societies. Unfortunately, 

 we have no agency in this country which is in a jMsition 

 to aid the spre.-id of scientific knowledge in a similar way 

 and on the same generous scale as the Smithsonian 

 Institution. 



