[26 



NATURE 



[July 31, 1890 



original idea was, partly by watching a storm-rain-gauge, 

 . and partly by estimation, to decide on the intensity of 

 the rain, and to indicate that intensity by moving the 

 pen further and further from zero as the fall becomes 

 heavier. Experience alone will show whether that is, or 

 is not, superior to moving it one step for each yjjjth of an 

 inch of fallen rain, which can be done by making a 

 Crosley rain-gauge send a current into the room where 

 the brontometer is placed, and strike a bell there. In 

 a heavy storm there will, however, be so much for 

 the observer to do, that very probably count would be 

 lost. It may, therefore, be necessary to make it act 

 automatically. 



The fourth pen is actuated somewhat like a piano. On 

 the occurrence of a flash of lightning, the observer presses 

 a key, the pen travels slightly to the right, and flies back 

 to zero. Referred to the automatic time-scale, this gives, 

 to a second, the time at which the key was depressed. 



The fifth pen is similar, but, being intended to record 

 the thunder, the observer will continue to hold down the 

 key until the roll is inaudible. The time of the departure 

 of this pen from zero will evidently be later than that for 

 the lightning by the time-interval due to the distance of 

 the flash, and possibly something may be learned from 

 the accurate record of the duration of the thunder. 



The sixth pen is similar to the third, and is intended to 

 record the time, duration, and intensity of hail. 



The seventh and last pen is devoted to an automatic 

 record of atmospheric pressure. As the rapid motion of 

 the paper, which is indispensable for studying the details 

 of a thunderstorm, has enlarged the time-scale more than 

 a hundredfold, it was imperative that the barometric scale 

 should itself be greatly enlarged. But the range of the 

 barometer in London is more than 2j inches, and no 

 enlargement less than ten times the natural (mercurial) 

 scale would be of any use ; hence a breadth of 25 inches 

 of paper would be necessary, unless some mode of shifting 

 the indication could be devised. 



Several plans were tried, but finally a modification of 

 Richard's statoscope has been adopted, which is so sen- 

 sitive that it will indicate the opening or shutting of a 

 door in any part of the house, gives a scale of 30 inches 

 for each mercurial inch {i.e. about three times that of a 

 glycerine barometer), and yet only requires 4 inches 

 breadth of the brontometer paper. Without entering 

 into all the details of construction, it is desirable to ex- 

 plain the general principle, and its application. As it 

 was essential that the apparatus should record accurately 

 to o'ooi inch of mercurial barometric pressure, it was 

 evident that friction had to be reduced to a minimum, 

 and considerable motive power provided. This is done 

 by placing in the base of the brontometer a galvanized 

 iron chamber, which contains about 3^ cubic feet of air ; 

 on the upper part are a series of elastic chambers, similar 

 to the vacuum boxes of aneroid barometers, but much 

 larger. When the instrument is to be put in action, these 

 chambers are connected with the large air-chamber, and 

 a tap is closed which shuts off communication with the 

 external air. Any subsequent increase, or decrease, of 

 atmospheric pressure will compress, or allow to dilate, the 

 air in these chambers, and the motion of the elastic ones 

 produces that of the recording pen. 



Obviously, any large change in the temperature of the 

 confined air would vitiate the readings ; but (i) the in- 

 strument is not required to give absolute, but merely dif- 

 ferential, values, and (2) the influence of the changes of 

 temperature is greatly reduced by the chamber being 

 surrounded with 4 inches thick of non-conducting mate- 

 rial, besides nearly i inch of wood outside of it. The 

 change of temperature in a room, and during the short 

 time that the statoscope will be worked without resetting 

 to zero {i.e. without opening the tap) has not hitherto 

 produced any measurable effect. 



G. J. Symons. 

 NO. 1083, VOL. 42] 



NOTES. 



The Societe de Physique et d'Histoire naturelle de Geneve 

 has decided to celebrate its hundredth anniversary. It was 

 founded in 1790, having originated in informal meetings of 

 eminent men of science who lived at that time in Geneva. On 

 October 23 a special meeting will be held, at which papers will 

 be read relating to the history of the Society and to the labours 

 of its members. It is hoped also that some honorary members 

 may be disposed to contribute to the success of the meeting by 

 sending scientific communications. In the evening there will be 

 a banquet. Members who intend to be present are asked to 

 write to M. de la Rive, the President, some days before the 

 celebration. 



The International Exhibition of Mining and Metallurgy, at 

 the Crystal Palace, was officially opened on Monday by Lord 

 Thurlow, F.R.S., one of the honorary vice-presidents of the 

 Exhibition. We shall give some account of the Exhibition 

 when the arrangement of the specimens is in a more forward 

 state. 



The British Medical Association is holding its fifty-eighth 

 annual meeting at Birmingham. The President, Dr. Willoughby 

 F. Wade, delivered the opening address on Tuesday. On 

 Wednesday Sir Walter Foster delivered an address in medicine ; 

 to-day Mr. Lawson Tait delivers an address in surgery ; and to- 

 morrow, at the concluding general meeting, Dr. W. H. Broad- 

 bent will speak on therapeutics. At the meeting to-day the 

 Association's gold medal "for distinguished service" will be 

 presented to Surgeon Parke, of the Emin Relief Expedition. 



The summer meeting of the Institution of Mechanical 

 Engineers is being held at Sheffield. It began on Tuesday> 

 July 29, and will not be concluded until to-morrow. The 

 following is a list of the papers : on steel rails, considered 

 chemically and mechanically, by Mr. Christer P. Sandberg, of 

 London ; on recent improvements in the mechanical engineer- 

 ing of coal-mines, by Mr. Emerson Bainbridge, of Sheffield ; 

 description of the Parkgate iron and steel works, by Mr. Charles 

 J. Stoddart, managing director ; description of the Sheffield 

 water works, by Mr. Edward M. Eaton, engineer ; description 

 of the Loomis process of making gas for fuel, by Mr. R. N. 

 Oakman, Jun., of London ; on milling cutters, by Mr. George 

 Addy, of Sheffield ; on some different forms of gas furnaces, by 

 Mr. Bernard Dawson, of Malvern ; on the Elihu Thomson 

 electric welding process, by Mr. W. C. Fish, of London 

 (communicated through Prof. Alexander B. W. Kennedy, 

 F.R.S., Vice-President). 



The Leeds Executive Committee, appointed for the purpose of 

 making arrangements for the visit of the British Association, 

 met on Monday. The Mayor, Alderman Elmsley, in opening 

 the proceedings, said that some of the most eminent men of 

 science in F-urope and America had announced their intention of 

 being present. Many of the principal manufacturers of I,eeds 

 had most generously consented to open their works for inspection 

 by members of the Association. Arrangements had also been 

 made for excursions to places of interest, historical or otherwise. 

 He had no doubt that the inhabitants of Leeds would show all 

 the hospitality and enthusiasm that was required; In the course 

 of the proceedings it was stated that it was the original intention 

 to have a guarantee fund of not less than ;^5oo, but that fund 

 now amounted to not less than ;,^6540. A report of the Execu- 

 tive Committee recommended that a call of 50 per cent, should 

 be made on the guarantors, but Mr. Benson Jowitt, in moving 

 the adoption of the report, expressed his belief that eventually 

 it would turn out that the call had been more than sufficient to 

 meet the demands which had been made upon it. The Vicar of 

 Leeds, Dr. Talbot, having seconded the adoption of the report,, 

 it was carried, and the proceedings terminated. 



