14 



NATURE 



[February 24, 19 16 



active in field soils to operate as a limiting factor in 

 crop production. 



Earthquakes are not frequent in West Africa, but 

 that they are not exceptional is the contention of M. 

 Henry Hubert, who has a paper on the subject in La 

 Geographic for November, 19 15 (vol. xxx.. No. 5). 

 From the information he has collected, which he 

 admits is incomplete, it appears that the region in 

 which earthquakes are most likely to occur is be- 

 tween longitudes 4° and 6° W., which coincides with 

 an area ■ of highly folded metamorphic rocks. The 

 earthquakes are seldom violent, but have been known 

 to reach eight on the scale of De Rossi. 



Tides tables for the eastern coasts of Canada and 

 for the Pacific coast for 1916 have been received from 

 the Department of the Naval Service of the Dominion 

 of Canada. It is claimed that, on the basis of length 

 of observation, the tables for the majority of the 

 \\estern ports of Canada are superior to those of any 

 port on the Pacific coasts of America, Asia, or Aus- 

 tralia. The tables for Prince Rupert are equal to 

 those for San Francisco, which are based on the 

 longest record of any published for the Pacific coast 

 by the United States Coast Survey. In the case of 

 the eastern ports the lengths of record for the ports 

 of reference — Quebec, Father Point, St. Paul Island, 

 Halifax, and St. John — are longer than those of any 

 Atlantic United States ports. These pamphlets are 

 apparently distributed free of charge to mariners. • 



The article by " G. H. B." in Nature of January 20 

 on the proposals regarding " Decimal Coinage and 

 the Metric System " which appeared in the Electrical 

 Review has called forth a rejoinder in the issue of 

 that journal for February 4. Our contributor writes 

 with reference to the reinarks in the Electrical Re- 

 view : — This correspondence has had at least one 

 good effect, namely, that it has forced the writer of 

 the articles in that journal to state clearly and 

 definitely which system of decimal coinage he proposes 

 to adopt. He would do well to remember that the 

 name "decimal coinage" is vague and meaningless, 

 since every country whicB has a small monetary unit 

 divided into still smaller cents calls that system a 

 decimal one. In the article in Nature the term was 

 purposely discussed in its most general aspect, and 

 if the writer in the Electrical Review considers this 

 to be an indication of "confusion," he and other 

 advocates of currency reform would do well to remem- 

 ber that they have only themselves to blame if endless 

 confusion arises from their failure to adopt a more 

 distinctive name for their system. We are now told 

 that the proposal would not have any effect on inter- 

 national commercial transactions conducted on a large 

 scale (the pound being unaltered), but that it would 

 alter the copper coinage. The change in the latter 

 would be far more confusing to the working classes 

 and the poor than the mere doubling or halving which 

 gave so much trouble in Austria, although it only 

 involved renaming the kreuzer while still retaining 

 the monetary value of that coin. The present reply 

 fully confirms the main contention of our article, 

 namely, that it would be a serious mistake to spoil 

 our prospects of adopting international standards of 

 NO. 2417, VOL. 96] 



weights and measures by associating them with a 

 proposal of so fundamentally different a character. 



The Electrical Review for February 4 contains an 

 illustrated article on the laboratory for heating and 

 ventilation, which has been opened at University 

 College, London, under the charge of Mr. A. H. 

 Barker. The equipment described consists mainly of 

 apparatus for measuring temperatures, radiated and 

 convected heat, the efficiencies of gas and electrical 

 radiators, for testing hot-water pipes, for determining 

 the slope of temperature through the walls to the out- 

 side, and for measuring- the resistances of air ducts. 

 Mr. Barker's laboratory appears to be the first one 

 established by any university for the special study of 

 the scientific problems of heating and ventilation, but 

 some important pioneer work on the scientific treat- 

 ment of ventilation was done by Sir Napier Shaw in 

 the Cavendish laboratory at Cambridge twenty years 

 ago. We welcome the inclusion of this work within 

 the sphere of the University, and hope that ere long 

 even those who now advocate the study of Greek 

 verse as an uprivalled educational training will look 

 on the scientific study of the problems underlying 

 everyday life as worthy of some consideration. 



Instrument-makers will find some useful sugges- 

 tions in a short paper by Mr. A. P. Trotter in the 

 Journal of the Institution of Electrical Engineers for 



February 



Trotter prepared some 



Numerals de»ign<.d by Mr. A. P. Trotter, min mum thickness. 



notes on the most suitable numerals for the scales 

 of measuring instruments; these were recently placed 

 at the disposal of the Meter Panel of the Engineering 

 Standards Committee, and have now been published 

 at their suggestion. Most of the figures which Mr. 

 Trotter proposes as "standard" combine the maxi- 

 mum of legibility and convenience with a considerable 

 degree of elegance; his 2, 3, and 7 are admirable. A 

 more open 5, with the vertical and horizontal lines 

 further to the right, may, however, be preferred ; and 

 this would enable the tails of the 6 and 9 (which it 

 is proposed should simply be an inverted 6) to be set 

 at a less violent and unconventional angle without 

 danger of confusion between the 5 and 6; the exten- 

 sion of the horizontal bar of the 5 to the right, beyond 

 the rest of the figure, would preserve its distinction 

 from the 3. A slightly wider 4 would also be an 

 improvement. 



One of the principal effects of the war on chemical 

 industry in this country has been to curtail largel\- 

 the supplies of sulphuric acid available, and to produce 

 an increased output of acid sodium sulphate or " nitre- 

 cake." In many cases it would appear possible to 

 utilise the nitre-cake as a substitute for sulphuric 

 acid. The Chemical Trade Journal of January 29 

 contains an article dealing with the question. A 

 special committee has been appointed in the West 



