August 30, 1888] 



NA TURE 



419 



simply in setting something burning : whereby not only 

 the fuel but the air was consumed, whereby also a most 

 powerful radiation was produced, in the waste waves of 

 which we were content to sit stewing, for the sake of the 

 minute, almost infinitesimal, fraction of it which enabled 

 us to see. 



Everyone knows now, however, that combustion is not 

 a pleasant or healthy mode of obtaining light ; but every- 

 body does not realize that neither is incandescence a 

 satisfactory and un wasteful method which is likely to 

 be practised for more than a few decades, or perhaps 

 a century. 



Look at the furnaces and boilers of a great steam-engine 

 driving a group of dynamos, and estimate the energy 

 expended ; and then look at the incandescent filaments of 

 the lamps excited by them, and estimate how much of 

 their radiated energy is of real service to the eye. It will 

 be as the energy of a pitch-pipe to an entire orchestra. 



It is not too much to say that a boy turning a handle 

 could, if his energy were properly directed, produce quite 

 as much real light as is produced by all this mass of 

 mechanism and consumption of material. 



There might, perhaps, be something contrary to the laws 

 of Nature in thus hoping to get and utilize some specific 

 kind of radiation without the rest, but Lord Rayleigh has 

 shown in a short communication to the British Association 

 at York : that it is not so, and that therefore we have a 

 right to try to do it. 



We do not yet know how, it is true, but it is one of the 

 things we have got to learn. 



Anyone looking at a common glow-worm must be struck 

 with the fact that not by ordinary combustion, nor yet on 

 the steam-engine and dynamo principle, is that easy light 

 produced. Very little waste radiation is there from phos- 

 phorescent things in general. Light of the kind able to 

 affect the retina is directly emitted, and for this, for even 

 a large supply of this, a modicum of energy suffices. 



Solar radiation consists of waves of all sizes, it is true ; 

 but then solar radiation has innumerable things to do 

 besides making things visible. The whole of its energy 

 is useful. In artificial lighting nothing but light is desired ; 

 when heat is wanted it is best obtained separately, by 

 combustion. And so soon as we clearly recognize that light 

 is an electrical vibration, so soon shall we begin to beat 

 about for some mode of exciting and maintaining an 

 electrical vibration of any required degree of rapidity. 

 When this has been accomplished, the problem of artificial 

 lighting will have been solved. Oliver J. LODGE. 



{To be continue. 1.) 



S TORM I VA RXINGS. 



'"TWENTY-EIGHT years ago, M. Le Verrier wrote to 

 *■ the Astronomer-Royal at Greenwich inviting the 

 co operation of this country in his scheme for giving 

 warning of storms by announcing them and following 

 their course by telegraph as soon as they appear at anv 

 point of Europe, and in the following year (1861) Admiral 

 FitzRoy established his system, giving notice of storms 

 before they actually strike our coast. Notwithstanding the 

 success which has attended these efforts, storms sometimes 

 overtake us before warning of their approach can be given, 

 and every endeavour to increase our foreknowledge of their 

 movements should be gladly welcomed. Since the vear 

 i860 much additional light has been thrown upon the sub- 

 ject by the systematic publication of synchronous charts, 

 such as those commenced by the late Captain Hoffmeyer, 

 Director of the Danish Meteorological Institute. Several 

 attempts have also been made to utilize the Atlantic 

 cables with the object of giving warning of storms leaving 

 the American coast or met with by the fast steamers 



' B.A. Report, i8Sr, p. 526. 



bound to the United States ; but these efforts have hitherto 

 met with little success from want of sufficient knowledge of 

 the conditions existing over the Atlantic, many storms pass- 

 ing wide of the British Isles, others originating in mid-ocean 

 or dying out there. Of the endeavours to connect our know- 

 ledge of the weather over the Atlantic with the reports re- 

 ceived from the two shores, the labours of Captain Hoffmeyer 

 as explained in " Etudes sur les Tempeies de l'Atlantique 

 septentrional : ' (Copenhagen, 1SS0), and recent publica- 

 tions of M. Ldon Teisserenc de Bort in the Annates of the 

 Central Meteorological Office of Erance, deserve especial 

 attention. With the view of utilizing the American 

 weather reports for the purpose of improving European 

 weather predictions, M. de Bort has made an investiga- 

 tion of the mean positions of high and low pressures in 

 the northern hemisphere for all winters since 1838, and 

 he shows how these great centres of atmospheric action 

 correspond to different types of weather, that during each 

 season these centres are limited in number, and that each 

 of them when displaced still lies within a definite area. 



During the winter season, for instance, the maxima are 

 arranged as follows : — (i) The maximum of Asia, which 

 generally includes two parts, one being near Irkutsk, 

 the other either in Siberia or Russia, one of the positions 

 being usually to the south-west of Tobolsk. (2) The maxi- 

 mum of Madeira, which is also sometimes split up into 

 two parts, one being over the ocean and the other over 

 Switzerland and Central Europe, or joining with a part of 

 the high pressures of Asia. (3) The Bermuda maximum, 

 which is often found over the east of the United States 

 or even in the neighbourhood of Nova Scotia, (.1) The 

 continental maximum of America, which usually lies over 

 the mountainous parts. (5) The Polar maximum, which 

 appears over Greenland, Iceland, or Norway. With 

 respect to the minima, there are (1) the low pressure 

 situated over the north of the Atlantic, which may be 

 called the Iceland minimum ; (2) a minimum which is 

 mostly to be found in America, generally over the region 

 of the Great Lakes ; and (3) a minimum which appears 

 to belong to the Arctic Ccean,and whose centre generally 

 lies near Nova Zembla. These mean positions are laid 

 down in recent barometrical charts, such as those of the 

 Meteorological Office and other institutions. The maxima 

 and minima may combine respectively, but there are 

 scarcely any' conditions where at least three centres of 

 high pressure and two centres of low pressure are not to 

 be found between China and California, and between the 

 equator and 8o c N. latitude. When the positions of the 

 high and low pressures are well known, we may proceed 

 like the naturalist, and discover, by the examination of 

 some portions, those that are wanting to the whole. The 

 introduction of this method into meteorology has a direct 

 application in the prediction of weather. The telegraphic 

 reports now received allow of the construction on one 

 hand of the isobaric chart over Europe (which ought to be 

 extended as far as Asia), and the isobars in their general 

 features over the United States ; between the two there 

 remains the great unknown of the Atlantic. Now by a 

 methodical discussion of the isobars of the two shores of 

 the ocean we ought to be able to reconstitute the conditions 

 over the Atlantic with a great amount of probability. 

 But how are we to know that there are not two or three 

 centres of depression over the ocean, for the number of 

 depiessions is not limited ? Evidently this is very difficult ; 

 but for the object in view — viz. to reconstruct the general 

 features of the isobars with sufficient accuracy to make 

 use of the data for forecasting the weather in Europe — the 

 difficulty is not so great. In fact, either the depressions 

 are grouped so as to be only the subsidiary disturbances 

 of a great minimum, and in this case the position of 

 the minimum may be indicated, which is the important 

 point, or they are completely separated, forming distinct 

 systems of low pressure, and then the trace of them is 

 found in the isobars on the coasts, and often even in the 



