56 



NA TURE 



\May 21, 1874 



We are probably yet a long way from any simple method, 

 suited for general adoption, for observing the Irue tempeiatiire of 

 the air at any place by means of the thermometer, so as to 

 eliminate completely the disturbing influence of radiation as 

 regards the thermometer and its protecting screen, or box. This 

 is a problem which may well engage the serious attention of the 

 chief observatories of this and other countries for some years to 

 come. The inquiry may be conducted by ascertaining the true 

 temperature of the air at different hours and seasons by Joule's 

 method, described in a communication to the Philosophical 

 Society of Manchester, November 26, 1867, and comparing the 

 results with those simultaneously obtained by thermometers pro- 

 tected in boxes of different constructions and materials. On 

 this point Wild's paper contains some very valuable observations 

 — valuable, not because they are conclusive, but because they are 

 suggestive, as indicating the line of inquiry which should be 

 pursued. In the meantime all that can be secured is iiniformily, 

 which would be sooner attained if meteorologists recognised that 

 the following jiositions of the thermometer are, on physical 

 grounds, inadmissible in researches into the horary fluctuations of 

 the temperature and humidity of the air, viz. the roofs ol houses, 

 close or near to walls, over bare soil, in the shadows of trees, 

 walls, or other obstructions, or outside windows. Let it be re- 

 cognised that observations made under these conditions are of 

 less, and in most cases of no value, then the adoption of 4 ft. as 

 the standard height would follow, and with it the question of 

 uniformity would be almost, if not altogether, settled. 



As regards i-ain-^aiiges, the Congress adopted as the best 

 form for the receiver of the rain-gauge the circular one, with a 

 diameter of 14 in., and at a height of 3 ft., or better 4', ft., above 

 the ground, a decision wdiich was agreed to by all the delegates 

 except Mr. Buchan, who lodged his protest against it. We 

 have taken the trouble of looking over Mr. Symons' last pub- 

 lished British Kaiiifall, and observe that there are not more 

 than half a dozen gauges in tlie British Isles of this dimension. 

 The readers of Nature are no doubt aware of the extensive 

 experiments and observations made on this subject m England 

 for some years past, and published annually in the British 

 Rainfall, irom which it has been experimentally proved that 

 gauges of all sizes from 3 in. to 24 in. inclusive collect amounts 

 not diffeiing more than 2 per cent, from each other. We have 

 had a communication from Mr. Scott, by which we are glad to 

 learn that the Meteorological Office has resolved to retain at 

 its stations the 8 in. gauges hitherto in use. This decision as 

 to the size of the gauge a future Congress will no doubt rescind. 

 Equally in eiTor is the decision as regards height of gauge 

 above the ground, especially large gauges. It is certain from 

 numerous observations made on the subject, that gauges 

 placed at from 3 ft. to \\ ft. above the ground will not indicate 

 with sufficient correctness'the amount ot the rain which falls at 

 the place of observation in cases where wind accompanies the 

 rain, owing to the disturbance caused by the obstruction offered 

 by the gauge itself, and by the eddies generated within the 

 funnel. Now owing to the enormous dragging influence of the 

 earth's surface of the wind, these disturbing effects are reduced 

 several fold at the surface and at one foot above it as compared 

 with 3 to 4.^ ft. high. On these grounds we cannot recommend 

 British Meteorologists to follow the decision of the Congress. 

 Owing to the extreme variableness of the rainfall, particularly in 

 such countries as Great Britain, where the surface is so uneven, 

 the proper observation of the rainfall requires twenty times more 

 observers than are required to observe any of the other meteoro- 

 logical elements. It is therefore well that a cheap gauge is also 

 a good one, since it facilitates an adequate observation, through 

 numerous observers, of the rainfall, which from its practical and 

 scientific bearmgs it is so important to know. 



In fixing the hours of observation it is essential that those 

 hours be selected which give approximately the mean tempera- 

 ture of the day. The combination of hours which seems to have 

 been roost approved both at the Leipsig Conference and the 

 Vienna Congress, and referred to by some very able meteorologists 

 as unconditionally the best, is 6 a.m., 2 p.m. and 10 r.M. The 

 merits of this combination consist in the equal interval of eight 

 hours between the observations, in the close approximation to 

 the daily mean temperature it affords, and in its suitableness 

 for tri-daily charting of the weather. It is, however, a combi- 

 nation of hours which, since it all but absolutely excludes the 

 hours of occurrence of the daily thermometric, baromelric, and 

 hygrometric extremes and means, cannot be recommended as 

 generally suitable for meteorological observations of aU coimtries. 



Indeed, its adoption in tropical and sub-tropical countries wotdd 

 be a blunder. As generally suitable for all latitudes, and for the 

 observation of the principal daily atmospheric phases of tempera- 

 ture, pressure, &c., the best hours are 9 a.m. 3 p.m. 9 p.m., or 

 10 .v. M. 4 P.M. 10 p.m., it being assumed that self-registering 

 thermometers are also used. 



We are glad to see that it has been proposed to convene 

 another Meteorological Congress in three years, and hope that 

 some of the questions that form the life-blood of the science will 

 be seriously and adequately discussed by the members of that 

 Congress. The more important of these questions are : — (i) 

 The position and protection of the thermometer for the tempera- 

 ture of the air ; (2) A more satisfactory method for observing the 

 humidity of the air, and of making the deductions therefrom ; 

 (3) The observation of earth-temperatures, especially at and near 

 the surface, and the depth at which fixed thermometers cease to 

 be suitable ; (4) Solar and. terrestrial radiation ; (5) The examina- 

 tion of the drying qualities of the air by atmometers, so as to 

 secure comparable results ; (6) A statement of the conditions 

 which anemometrical stations ought to fulfil, so that the instru- 

 ment shall indicate the true movement of the air over the region 

 where it is placed, or, if this be unattainable, a means of valuing 

 the observations so as to approximate to it ; * (7) Anemometers 

 {Wild's, &c.) for stations of the second order, with which trust- 

 worthy observations of wind -force may be made ; and anemo- 

 meters of velocity which admit of their errors beingreaddy ascer- 

 tained from time to time ; (8) an adequate nomenclature of 

 clouds ; and (9) the question of atmospheric electricity. 



Though the Vienna Congress can properly be regarded as 

 having only concerned itself with questions lying on the outskirts 

 of meteorology, it has done commendable work in thus paving 

 the way for future Congresses, entering on the really important 

 practical questions which united action on the part of meteoro- 

 logists can alone settle. Until tolerable uniformity be arrived at 

 as regards (i), (2), (5), (6), (7), and (8), in the above paragraph, 

 meteorologists can scarcely be said to have begun to collect data 

 of such a nature as will satisfy our best physicists, and thus lead 

 them to undertake the investigation of the more important of 

 the intricate and difficult problems of the science. 



M. COGGIA'S COMET 

 "T'lIE following is an epheraeris to the comet discovered by M. 

 Coggia. It will be seen that the comet will be vastly in- 

 creased in brilliancy by the month of August. 



Brightness 

 Berlin Mean time. R.A. D. ", (brightness at time 



of discovery = i). 



Royal Society, May 7, — Note on some Winter Thermometric 

 Observations in the Alps, by E. Frankland, F.R.S. 



During the past winter the author spent a fortnight at the vil- 

 lage c{ Davos, Canton Granbimden, Switzerland, and had thus 

 an opportunity of experiencing some of the remarkable peculiari- 

 ties ot the climate of the elevated valley (the I'rattigan) in which 

 Davos is situated. The village has of late acquired considerable 

 repute as a climatic sanitarium for persons sulfering from diseases 

 of the chest. 



