October 31, 1901] 



NA TURE 



649 



A Curious Flame. 



The following experiment with a Bunsen flame may interest 

 some of your readers. 



A Bunsen burner is lighted below and turned down so that 

 the escaping gases will no 

 longer burn at the upper 

 end of the lube. The end 

 of a glass rod is placed in 

 the stream of gas and a 

 lighted taper applied to it. 

 The gas now burns steadily 

 and the flame takes the form 

 of a finger-stall attached by 

 one point to the rod. A 

 little adjustment of the gas 

 supply may be required. A 

 glass tube filled with water 

 will not serve, which sug- 

 gests that the rod must have 

 a temperature of more than 

 100° C. Wires of any com- 

 mon metal may be used 

 instead of the glass rod. It 

 is a beautiful experiment. 



The above came under 



my notice about six months 



ago when experimenting 



with flames, and I can find 



no reference to it in any 



book or journal. Perhaps some of your readers can give me 



information. L. L. Garbott. 



Winchester College, October 20. 



THE LONDON FOG INQUIRY. 



THE action of the County Council of London in 

 devoting a sum of money for the purpose of 

 aiding the Meteorological Council in making an inquiry 

 into the occurrence and distribution of fogs in the 

 London district has attracted public attention to an 

 undertaking which is in itself of a very unambitious 

 character. The discomforts and dangers of a London 

 fog are indeed a loud challenge to the scientific and 

 practical intelligence of Londoners, but what is aimed at 

 in the present case is not any heroic attempt to deliver 

 London from its insidious enemy, but the collection of 

 information as to the best mode of attacking the purely 

 meteorological question of local forecasts. In the 

 language of the hour, it is a scouting expedition and not 

 an attack in force. 



Whether such a preliminary inquiry will of itself yield 

 results that are either novel or valuable is still to some 

 extent a matter of opinion. It originated in a request 

 from the electric lighting authorities of several districts to 

 be supplied, for obvious reasons, with forecasts or warn- 

 ings from the Meteorological Office of the probable 

 occurrence of serious fogs. \'ery much is already 

 known about fogs. Apart from the special investigations 

 of Dr. Russell and others, the students of weather maps 

 are quite familiar with the general meteorological con- 

 ditions under which fogs are likely, and recognise e\en 

 more easily the conditions when they are unlikely. 

 Besides this more or less technical knowledge, there is a 

 large and increasing store of e.xperience of fogs amongst 

 the millions of dwellers in the London district. From 

 recent circumstances I am able to say that he who would 

 select an abode in London can obtain much curious 

 information on the subject from friends, scientific and 

 otherwise. It may take the form of testimony as to the 

 relative prevalence of fog in other people's localities or 

 its intolerable prevalence in his own, according to the 

 temperament of the witness. It must, perhaps, be allowed 

 that it is a rash undertaking to controvert the state- 

 ment that the phenomena of London's fogs are well 

 known. 



NO. 1670, VOL. 64.] 



Yet when one is brought face to face with the practical 

 question, " Can you give us an hour's warning of the 

 approach of a fog in any particular district?" one is 

 driven to realise that, after all, the abundant knowledge 

 based on the prolonged experience of many observers 

 lacks coordination. If conditions are favourable for the 

 occurrence of fog, which part of London will be the first 

 to experience it ? and at what rate will it spread or move 

 to other parts? and where will it be most dense? Will 

 it begin on the river and gradually extend to the heights, 

 as a sea fog pours over the land ? or will the heights 

 first cover themselves with mist rolling down to the 

 vallevs ? or if some locality is specially favoured as com- 

 pared with others, by what numerical or percentage 

 estimate should the advantage be estimated? 



Statistical answers to these questions are clearly 

 within reach. One year's experience will give no final 

 statistical results, but it may at least give an indication 

 of the possibility and prospect of obtaining such results. 

 Some preliminary understanding must be arrived at as 

 to the method of describing the experience of the 

 different observers. There are fogs of many colours 

 and of diverse character and density ; some are on the 

 surface, others, which do not come so low even as the 

 tops of buildings, produce at noonday the darkness of 

 night. It may be assumed that these differences of type, 

 as well as differences of distribution, are not entirely 

 capricious, but are related to sotne specific differ- 

 ence in the meteorological conditions, general or local, 

 the local topography and conditions of the surface, 

 01; the local geology. All these things can also 

 be ascertained, but whether the differences are suffi- 

 ciently marked as to be recognisable in individual 

 cases and to form a basis for forecast work is a question 

 which, with all deference to the opinion of those who 

 regard the phenomena of fogs as known, is worthy of 

 investigation. Nor is it even easy, when one considers 

 the difficulty of securing uniformity of convention among 

 observers and uniformity of exposure of thermometers 

 and other instruments. It is a question that requires to 

 be approached, if confusion is to be avoided, with the 

 intelligence of trained scientific scepticism. 



The County Council, while authorising the organisa- 

 tion of observations at the fire stations by the staff of the 

 fire brigade and possibly at other institutions under the 

 control of the Council, have assigned to the Meteorological 

 Office the responsibility for the conduct of the investiga- 

 tion and for providing all necessary instruments. The 

 Office is also expected to make arrangements for observa- 

 tions outside the administrative County of London. The 

 organisation of the details of such cooperation is not 

 without its difficulties, but the cordiality with which the 

 County Council has expressed its desire to cooperate 

 is a weighty element in favour of the success of the 

 attempt. It is obvious that without such cooperation 

 the organisation of an efficient system of volunteer ob- 

 servations would be a matter of great labour, and 

 prolonged delay. 



I have been careful to indicate the limitation of the 

 immediate scope of the present inquiry to the collation 

 of local observations of fog, and perhaps of temperature 

 of air and water, with other local data and the general 

 meteorological conditions. This is mainly a matter of 

 appropriate organisation. There are, however, some 

 physical aspects of the formation of vapour in the atmo 

 sphere which may be of service as a guide to the classi- 

 fication of the conditions of distribution of fog. In the 

 foiefront 1 would place the question as to what is the 

 source of supply of the water which is the main con- 

 stituent of those fogs which are not simply wreaths of 

 smoke. Does the water come from the ground on 

 which the fog lies ? or the air in contact with it ? or from 

 some higher or more distant region? It is a matter of 

 common observation that a surface of relatively hot 



