63^ 



NA TV RE 



[October 29, 1903 



corporations and others distributing electrical energy. In 

 course of time the benefits to the electrical industry at large, 

 which will certainly follow the adoption of these standard 

 pressures, must become more and more apparent. 



A circular was drafted embodying the suggestions of the 

 subcommittee, and this was submitted, first to the manu- 

 facturers for their consideration, and secondly to the lead- 

 ing consulting engineers and users of motors. 



The information so courteously placed at the disposal of 

 the subcommittee by the consulting engineers and manu- 

 facti^rers was most carefully weighed and considered by 

 the subcommittee, and certain definite conclusions were 

 arrived at, the circular being sent, in the first instance, to 

 the manufacturers, as they were the people most directly 

 interested. Replies were received from all the leading 

 firms, who expressed themselves unanimously in favour of 

 the recommendations of the subcommittee. The consulting 

 engineers similarly gave their adherence to the proposals 

 of the subcommittee. 



Before coming to their final decision the subcommittee on 

 generators, motors and transformers conferred with the sub- 

 committee on electrical tramways, of which Mr. A. P. 

 Trotter is chairman, and a joint meeting took place, with 

 the result that the pressure of 500 volts, which most con- 

 cerned the latter subcommittee, was agreed to, and in 

 addition to the pressures already agreed to 600 volts was 

 decided upon as the standard pressure for electrical rail- 

 ways. 



The question of the adoption of standard frequencies, 

 although of equal importance with that of standard 

 pressures, was not surrounded with the same difficulties. 

 It was, however, deemed advisable to fix upon the standard 

 frequencies at the earliest possible stage of the work, as 

 no progress could be made in the standardisation of prime 

 movers for driving alternate current machinery until such 

 time as the frequencies had been settled upon. On this 

 question there appeared to be a great preponderance in 

 favour of frequencies of 25 and 50. The only point upon 

 which any serious difference of opinion appeared to exist 

 was the advisability of the adoption of a third frequency 

 of 40 or 42, to enable rotary converters to be used to the 

 fullest advantage. All the arguments in favour of this 

 third frequency were fully discussed, but after carefully 

 weighing the pros and cons the subcommittee decided not 

 to rp'-ArnmenH \\\p adoption of more than two frequencies, 

 namely, 25 and 50. 



The recommendations of the subcommittee were then sub- 

 mitted to the electrical plant committee, the publication 

 committee, the main committee, and the Board of Trade 

 for their approval. 



This having been obtained, it was deemed advisable, in 

 the interests of the electrical industry of the country, that 

 the findings on the questions of direct current pressures 

 and frequencies should be published at an early date, with- 

 out waiting for the completion of the entire report to be 

 issued at a later date. 



The following are the resolutions on standard direct 

 current pressures and standard frequencies : — 



(i) That the standard direct current pressures, measured 

 at the consumers' terminals, be : — 



no, 220, 440, 500 volts. 



(2) That the standard direct current pressures, measured 

 at the terminals of the motors, be : — 



For tramways 500 volts. 

 For railways 600 volts. 



(3) That 25 periods per second be the standard frequency 

 for : — 



(a) Systems involving conversion to direct current by 



means of rotary converters. 

 {h) Large power schemes over long distances, 

 (c) Three phase railway work, where motor gearing 



and the inductive drop on the track rail have to be 



considered. 



(4) That 50 periods per second be the standard frequency 

 for : — 



(a) Mixed power and lighting on town supply mains. 

 (h) Ordinary factory power plant. 



(c) All medium size power plant where rotary converters 

 are not employed. 



NO. 1774. VOL. 68] 



GEOGRAPHY AT THE BRITISH 

 ASSOCIATION. 

 ^PHE present transitional phase of geographical thought 

 •*• and activity was faithfully mirrored in the proceedings 

 of Section E. The majority of the papers revealed the 

 wide range of geographical interests rather than any great 

 advance in geographical coordination. In this they are 

 typical ; for while there are many workers at geographical 

 problems, few, if any, would put forth the claim of being 

 complete geographers. There are indications of many 

 geographical specialisms being recognised. Their ex- 

 ponents are, however, at one disadvantage when compared 

 with other specialists. An organic chemist usually has had 

 a thorough training in chemistry before he specialises in 

 organic chemistry. Few geographical specialists have had 

 any training as geographers. Each makes his own con- 

 tribution, but it is often an isolated one, and does not fit 

 into a general plan of the subject. The unity of geography 

 and the relation of^ts parts are very gradually being eluci- 

 dated. The want of this coordination is strongly felt by 

 most geographical workers. At the conclusion of the 

 Southport meeting one wished for a summary coordinating 

 the communications discussed. Perhaps this is felt, 

 though to a less extent, in other sections, and it would be 

 useful if the presidential duties were made to conclude by 

 the giving of a brief review of the work done at the section. 

 The address of the genial president, Captain Creak, was 

 the onlv one which surveyed the whole world. It was on 

 terrestrial magnetism, and has already been printed. Dr. 

 Vaughan Cornish's researches, summarised in the report 

 of the committee on terrestrial surface waves, are on world- 

 wide phenomena, which he illustrated on this occasion 

 mainly by beautiful views of the wave forms of Niagara, 

 from which he has recently returned, and by pictures of 

 wave forms in snow and on quarry roads caused by heavy 

 sledge traffic. 



The section was also privileged to hear an address from 

 Prof. Pettersson, of Stockholm, who spoke for an hour in 

 excellent English, on the effect of ice melting on oceanic 

 circulation. Prof. Pettersson has long insisted that the 

 thermodynamic cycle of latent heat, consisting of ice form- 

 ation in polar regions and of ice melting in sea-water in 

 lower latitudes, was a potent cause of oceanic currents. 

 H- has calculated that the ice melting between Iceland and 

 Jan Mayen generates about 400,000 horse-power annually, 

 which is expended in accelerating the water movements of 

 th^ east Iceland polar current. The energy set free on ice 

 melting in sea-water maintains a kind of inverted water- 

 fall, an upwelling of bottom water to the surface. 

 Warm currents follow the trend of deepest isobaths, ice 

 currents exist only in shallow seas, where no warm current 

 can melt them. Ice currents and warm currents meet 

 between Iceland and Jan Mayen, west of Spitsbergen, south- 

 east of Newfoundland, and round the margin of the ice- 

 girdled Antarctic. The " outbursts " of Antarctic ice- 

 bergs which carry them to low latitudes m the Indian 

 Ocean may influence the climate of India and Australia. 

 The latest Antarctic outburst and series of great droughts in 

 India occurred between 1891-98. Prof. Pettersson^ con- 

 sidered that regular surface observations between 60 and 

 100° E. and a few series of deep-sea soundings would 

 reveal hydrographical variations with important meteor- 

 ological bearings. He also pointed out that current 

 measurements at depths of 800-4000 metres in the Atlantic 

 were needed to ascertain the significance of the currents 

 generated by ice attraction. At the conclusion of his paper 

 Prof. Pettersson showed in miniature an experiment to 

 illustrate the effect of melting ice in causing currents in 

 salt water carried out by Mr. J. W. Sandstrom, assisted by 

 Miss A. Palmquist, who have made a series of useful calcu- 

 lations from the data obtained from this experiment. 



Travellers' tales were few, but full of human interest. No 

 one who heard Lieutenant Shackleton will forget the vivid 

 and racy account he gave of the National Antarctic Ex- 

 pedition. Dr. Tempest Anderson's slides and descriptions 

 of the volcanic phenomena of St. Vincent and Martinique 

 were equally effective. Lieut. -Colonel Manifold described 

 his journeying from India across China, and back over 

 different routes through the heart of the Empire. In his 

 paper were many hints of the great activity of other Powers 



