12 



NA TURE 



[May 3, 1894 



the Cataract Construction Company's canal, and pass 

 it after use into the tunnels belonging to this Com- 

 pany. The turbines drive a vertical shaft which, at 

 the surface of the ground, is geared by bevel wheels 

 to the main shaft, on which are the pulp grinders. 

 This is the only case likely to occur where the 

 power is used directly. In all other cases it is likely 

 to be transmitted electrically. The first electrical 

 application is to the works of the Pittsburgh Reduction 

 Company for the manufacture of aluminium. The 

 Niagara Falls Power Company has undertaken to supply 

 them with continuous current at i6o volts to the extent 

 of 7000 horse-power. The first 1 500 horse-power is now 

 being put in. In order to do this, Prof. Forbes has arranged 

 to carry the alternating current by two circuits in two 

 phases. This is the character of current generated by 

 the dynamos. At the works. 2500 feet from the power- 

 house, the current is to be transformed from 2000 volts 

 to IIS volts alternating. It is then passed through three 

 of the commutating machines, like those shown by 

 Schuckert and others at the Frankfort Kxhibition of 1S91. 

 These are continuous current machines, each with four 

 rings attached to certain bars of the commutator. The 

 alternating current is passed to these rings by brushes : 

 the armature revolves synchronously with the generator 

 in the power-house and with the turbine. The other 

 brushes, which rub on the commutator, give off con- 

 tinous current to the aluminium baths at 160 volts, the 

 E.M.F. being (in normal conditions) raised in its change 

 form alternating to continuous current in the ratio of 

 'Ji : I. A shunt direct current with variable resistance 

 in the circuit excites the field magnets. It is found that 

 the electromotive force of the direct current can thus be 

 regulated. The explanation of this remarkable fact has 

 been worked out by Mr. Steinmelz. The whole of this 

 plant, transformers, commutating machines, and switch- 

 board was tendered for by different firms, and the bid 

 of the General Electric Company has been accepted ; 33 

 per cent, of spare plant is held in reserve The dynamos 

 and power-house switch-board, on the other hand, arc in 

 the hands of the Westinghouse Company. It is expected 

 that both types of machinery will be in operation in the 

 course of a few months. 



The patent for Prof. Forbes' construction of dynamo, 

 which is being built, has been just allowed by the United 

 States Patent Office. One object to be attained was to 

 have a fixed armature, so that the armature might be 

 wound so as to give a very high E.M.F. without being sub- 

 jected to the enormous centrifugal forces of the revolving 

 part. Another object was to attain a maximum lly-wheel 

 effect with a minimum weight. The revolving parts of 

 the turbine and dynamo, and the vertical shaft connect- 

 ing them, are all supported hydraulically by means of a 

 piston in the turbine. The supporting power of this 

 piston limited the weight of the revolving part of the 

 dynamo to 80,000 lbs. The governor of the turbine de- 

 manded (to fulfil the required conditions of regulation) 

 a momentum equal to that of 1,100,000,000 lbs., moving 

 at the rate of 1 foot per second. 



I'.olh of these objects are attained by Prof. Forbes' 

 construction, which conbists in making the armature 

 fixed and ring-shaped, with a space inside for getting at 

 the l.<-.ir;n '.i. ,ind in making the fields of a bell-shape, 

 th' :.g on the inside of a nickel steel ring, which 



is , , : by the top piece or cover, which in its turn 



is rigidly fixed to the vertical axis. This novel con- 

 struction gives all the ily-wheel effect required without 

 making the weight too great. Every design which had 

 been made previously rei-piired the addition of a lly- 

 wheel costing at '■ or /looo. The construction 

 for whirh Prof, f -nl has now been granted has 

 al t merit thai the magnetic pull between the 

 ar- I the fields tends to diminish the breaking 

 strain d tnirifugal force on the revolving part to a very 



NO. 1279, VOL. 50J 



sensible amount. When the revolving part is inside the 

 magnetic pull assists centrifugal force in its destructive 

 effect. 



THE EPPING FOREST CONTROVERSY. 



•TrHE meeting of the Essex Field Club, which, as we 

 •'■ announced last week, had been convened for the 

 inspection of the thinned districts of Epping Forest, was 

 in every way a remarkable gathering. Nearly 150 

 members and visitors assembled in Monk's Wood, 

 among them, in addition to the conductors and officers 

 of the Club, being Sir John Lubbock, Mr. J. Bryce, 

 M.P., Chancellor of the Duchy of Lancaster, Prof. 

 Boulger. Prof. W. R. Fisher, Dr. Church, Mr. Arthur 

 Lister, .Mr. .\ndrew Johnston (chairman of the Essex 

 County Council), Mr. David Howard, Mr. Salmon (chair- 

 man of the Epping Forest Committee), Sir Frederick 

 Young, Mr. Bernard Gibson, and others interested in the 

 question of the Forest management. .A. thorough ex- 

 amination of Monk s Wood was made, Mr. E. N. Buxton 

 giving a detailed explanation of the policy which the 

 Conservators had been pursuing, and pointing out the 

 reasons that had led to the present necessity for thinning. 

 The party were then conducted to Lord's Bushes, which, 

 as an example of the beautifying effect of judicious 

 thinning, is almost unrivalled, this district having been 

 submitted to the operation repeatedly since the Forest 

 was taken over by the present Conservators, .-\fler te.i 

 at the Royal Forest Hotel, Chingford, a meeting of the 

 Club was held, Mr. F. Chancellor, the President, in the 

 chair. The discussion was opened by Prof. Meldola, 

 who commenced by explaining that the statements which 

 had been inserted in the newspapers respecting the 

 attitude taken by the Club in the present controversy had 

 been made without authority, and were devoid of founda- 

 tion. He then went on to show that the observations 

 made by him in 1SS3 in connection with the agitation 

 against the railway scheme with which the Forest had 

 then been threatened (see the article quoted in our 

 columns in last week's note\ had recently been applied 

 to the present thinning operations without his concur- 

 rence, and in direct opposition to the views which he had 

 formed after five visits to the districts now being donl' 

 with, and after an intimate acquaintance with the Fon 

 for a period of more than twenty years. Having l . . 

 plained the general grounds on which he based his opinions, 

 he slated that in his belief the Forest as a whole showed 

 a marked improvement since it had been under the care 

 of the present management, and he considered that 

 much of the recent criticism had been most unjr 

 and the newspaper accounts exaggerated to an extc 

 bordering on the ludicrous. Two or three speakers took 

 an adverse position, but Prof Boulger, Mr. Howard, 

 Mr. F. C. Gould. Mr. W. Crouch, the President, Mr. 

 William Cole, and others who knew the Forest well, ex- 

 pressed general approval of the recent operations. Mr. 

 Angus Webster, the Duke of Bedford's forester, who 

 accompanied the party, was of course obliged to reserve 

 his opinion owing to his official connection with the com- 

 mittee of experts appointed by the Corporation, the 

 report of this commitlec not having as yet been 

 presented. As the outcome of the discussion, it may 

 safely be said that the public will not be so ready 

 in future to give credence to the opinions of irre- 

 sponsible and inexperienced scribblers who, often with 

 the best of motives, may seriously hamper the work of 

 the Conservators in iheir endeavour to restore the Forest 

 to a more natural condition in those parts which have 

 for so many centuries been made unnatural and unsightly 

 by the existence of the rights of lopping. Although it 

 had not been the original intention of the oMicers and 

 conductors to allow a formal motion to be put, a strong 

 desire was expressed that this should be done, and on 



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