Nov. 6, 1884] 



NA TURE 



7 



penetrative energy, and go through a thickness of what are 

 ordinarily considered opaque substances, but which are inter- 

 cepted by the contents of the epidermic pigment cells largely 

 developed in the African, a little more sparingly in Hindoos, 

 and not absolutely wanting in the sunburnt excursionist or 

 Sportsman in our own country. 



Tin- Australian will tell you that he has done hard work — in a 

 sb.iik ti mperature of 100" — in the sun in a light wideawake and 

 not felt exhausted ; while continuous labour of some hours in 

 much less heat — 75° in the shade and exposed to the sun — in 

 Hindostan would be simple destruction of the European's powers 

 of exertion with all a Bond Street hatter could devise on his 

 head. A. T. Fraser 



Equator of Heat, India, October I 



The Distribution of Scientific Works Published by the 

 British Government 

 I have read Dr. Valentine Ball's letter in your journal of 

 October 30 (p. 6541 expressing his astonishment that the scien- 

 tific Reports of the British Government are not presented to the 

 leading American scientific institutions. It may surprise Dr. 

 Ball to learn that the Treasury recently refused to present one 

 of tin- largest -cientific libraries in Dublin with copies of the 

 irts on the ground that their "free list" was 

 too limited ! G. F. B. 



A NEW METHOD OF HEATING IN THE 

 REGENERATIVE GAS FURNACE 



DURING the present age, which may be called that of 

 Electricity, the sister science of Heat is not receiv- 

 ing so much attention at the hands of the natural philo- 

 sopher as it did formerly. But still there remain some scien- 

 tific men who are giving a life-long attention to it — MM. 

 Hirn and Berthelot in France, Herren Clausius, Helm- 

 holtz, and Frederick Siemens in Germany, Mr. Joule 

 and Sir William Thomson in this country. During the 

 late Sir William Siemens's lifetime, the one brother 

 worked here in the science of Heat, the other in 

 Germany, and the work of both was applied everywhere : 

 now Mr.' Frederick Siemens works alone, and, from the 

 recent evidence of that work, it promises to play .111 im- 

 portant part in the economical application of fuel. Mr. 

 F. Siemens has recently had an opportunity given him of 

 (■ringing his views forward in this country, having read a 

 paper at the Chester meeting of the Iron and Steel Insti- 

 tute on a new method of heating in the regenerative gas 

 furnace, in which he treated the practical side of the 

 question, whilst in the discussion of the same paper he 

 gave his views on the theory of the subject. Mr. F. 

 Siemens's investigations have led him to the conclusion 

 that combustion can only be perfect, and be maintained 

 perfect, if the space in which it takes place is sufficiently 

 large to allow the gases to combine out of contact with 

 schl materials. Having proved by actual experiment 

 that solid substances interfere with the formation of flame 

 and that flame injures solid substances with which it comes 

 in contact, he brings forward an hypothesis to account 

 for the phenomena. According to the electrical hypo- 

 thesis, which Mr. Siemens prefers, flame is the result of an 

 infinite number of exceedingly minute electrical flashes, 

 the dashes being due to the exceedingly swift motion of 

 gaseous particles, and a solid body which opposes itself 

 to these flashes is cut by them, whilst, the motion being 

 more or less arrested by the solid body, the flame is 

 damped. 



her important deduction from these investigations 

 is that combustion should be considered in two stages or 

 periods, which may be respectively called active and neu- 

 tral. In the first the purely chemical combination of the 

 gases takes place, during which, as soon as the tempera- 

 ture of ignition has been reached, the whole of the heat 

 of the highest possible intensity is produced, of which a 

 large portion is given off by radiation, whilst in the 

 second the temperature having fallen in the proportion of 



the heat given off by radiation, the remainder of the heat 

 which is no longer of an active character, is best trans- 

 mitted by conduction. For the purpose of utilising this 

 portion of the heat, as well as for raising the temperature 

 of the gas and air before combustion, the regenerators 

 are requisite which form an essential feature of all fur- 

 naces worked at an intense heat on the Siemens principle, 

 care being taken to design the furnace so that the gases 

 shall have combined perfectly before the products of 

 combustion are allowed to pass away. 



Mr. Siemens in applying his investigations to practice 

 insists that flame must not be allowed to impinge upon 

 bodies to be heated, but must simply heat the bodies by 

 radiation, and furnaces must be so constructed as to allow 

 the flame to develop out of contact, not only with the 

 substance on its bed, but with the walls and roof of the 

 furnace itself ; it thus follows that large furnaces must 

 replace small ones, and to meet the objection that the loss 

 of heat into the atmosphere must increase in the pro- 

 portion of the area of the furnace, Mr. Siemens explains 

 that the heat developed in the furnace increases in a 

 much larger ratio than its increase in area, because 

 flame radiates in every direction from every portion of 

 its entire volume, while a solid substance radiates from 

 its external surface only. The details of construction of 

 metallurgical and glass furnaces and of steam-boilers are 

 given in the paper in question, and need not be considered 

 here ; the main point is that furnaces heated on the 

 radiation principle have been proved both in Dresden 

 and at Landore to have been economical of fuel, whilst 

 the saving in the materials treated from reduced oxidation 

 and in the construction of the furnace has been found to 

 be very great. 



There is another point of view of this important ques- 

 tion which is daily demanding and commanding more 

 attention, and that is the abatement of the smoke 

 nuisance. As is well known, smoke is but incomplete 

 combustion, and the only way to get rid of it is not to 

 produce it. Mr. Siemens insists that this can only be 

 effected by not permitting flame to touch any substance 

 whatever so long as it exists in the active condition ; for, 

 just as carbon is precipitated upon a glass rod put into 

 an ordinary gas flame, so is it with any flame whatever 

 its temperature ; but the greater the difference of tem- 

 perature between the flame and the body brought into 

 contact with it the greater will be the amount of smoke 

 produced. Mr. Siemens tells how in Dresden he suc- 

 ceeded in extending his works, without the production of 

 smoke, by the application of the system of heating he 

 recommends, and trusts that here also not only may smoke 

 be abated, but that the public may also derive benefit 

 by manufacturers being able to supply goods at cheaper 

 rates owing to being able to economise their fuel and the 

 material heated within the furnaces as well as that of 

 which the furnaces are constructed. 



THE PRIME MERIDIAN CONFERENCE 



THE greatly extended and ever increasing intercourse, 

 both commercial and scientific, which lias -town up 

 between different nations in modern times has naturally 

 caused especial attention to be drawn to the question of 

 assimilation of the different systems of reckoning em- 

 ployed. Weights and measures and money have been 

 already dealt with more or less successfully, but always 

 with steady advance in the direction of unification. More 

 recently, and in like manner because of practical diffi- 

 culties and inconveniences, unification of the methods of 

 counting longitude and time has in its turn become a 

 question pressing for solution by the establishment of 

 some international agreement in regard to all matters 

 relating thereto. 



The subject became first systematically discussed at 

 the Conference of the International Geodetic Association 



