NA TURE 



[April'], 1 88 1 



lengths, I was led to the discovery of some simple relations, the 

 furdier study of which will perhaps one day help to simplify the 

 theoiy of flames. By specific flame-length I mean the length of flame 

 of a combustible gas burning in a normal atmosphere at a standard 

 rate through a simple circular orifice under such conditions as to 

 produce a symmetrical, vertical, steady flame capable of beini; 

 measured. These conditions are not difficult to obtain in tlie 

 case of coal gas. In fact for a very long time a flame-length 

 test has been in use amongst gas-makers, but as the comparison 

 has not always been made on the basis of volume the results 

 have not always been satisfactory. The system I advocated \\as 

 that of stating the flame-length for some standard rate. It 

 occurred to me at that time that the flame-length should be pro- 

 portional to the consumption or rate of issue of the gas. On 

 submitting this theory to experiment I obtained satisfactory 

 evidence that such was the case, as the following table taken at 

 chance from a series of experiments will show : — 



Calculated rate for 

 lo" flame. 

 Cubic feet. 



375 

 377 

 375 

 37° 

 375 

 371 



» 2'9» 372 



I have therefore formulated the following laws : — 



1. That the flame-length of a combustible gas is proportional 

 to tlie consumption. 



2. That the flame-length is the distance travelled by a gas in 

 obtaining oxygen for its consumption. 



3. That the flame-lengths of diff'erent gases are proportional 

 to the relative amounts of oxygen required for their combustion. 



The last remains to be proved, and 1 have been led to experi- 

 ment upon simple gases such as hydrogen, carbonic oxide, and 

 sulphuretted hydrogen, with the object of determining their 

 specific flame-lengths; but these gases give flames offering gi-eat 

 difficulties in measurement. The flames given by coal-gas under 

 suitable and easily-obtained conditions ofl'er no difficulty, but I' 

 have not been able at present (owing to the difficulty mentioned 

 above) to obtain very satisfactory results with the above-men- 

 tioned three simple gases. Other simple gases have suggested 

 themselves, but the cost of preparing them in a state of purity 

 in sufficient quantity has at present prevented their use. How- 

 ever, with regard to sulphuretted hydrogen and carbonic oxide, 

 I have found their flame-lengths stand in the relation of V2 

 to I. -^ 



In view of the difficulty of measuring the flames of these 

 simple gases I am about to effect the determination by indirect 

 means. By preparing mixtures of known composition that will 

 give easily-measurable flames, I hope to be able to throw some 

 light upon this subject of flame-lengths. 



March 22 Lewis T. Wright 



Future Development of Electrical Appliances 

 As many of your readers have doubtless read Prof. Perry's 

 interesting paper on the future development of electrical appli- 

 ances, a remark on one or two points might not be out of place. 

 In speaking of the application of electricity to railway travelling, 

 Prof. Perry says tliat the weight of the train would be mucli 

 reduced under the proposed conditions, and rail friction woull 

 be minimised. It strikes us that to have light trains would not 

 be altogether an advantage, for .several reasons. The lighter the 

 train the less profitable would be tlie vis viva against a strong 

 vfind (and the latter is an important element in railway locomo- 

 tion). Again, the stability of a heavy carriage is much greater 

 than that of a light one, and a heavy engine in front of the train 

 must steady the whole system. It would be interesting to ascer- 

 tain from a practical engineer whether a train of six coaches with 

 self-propelling powers could safely run at a speed of fifty-eight 

 miles an hour. George Ravleigh Vicars 



WoodviUe House, Rugby 



Prehistoric Europe 

 I AM sorry to have to ask yon again to allow me to correct 

 some statements made by Prof. Dawkins in the matter of the 

 Victoria Cave explorations (Nature, vol. xxiii. p. 482). 



1. He says that "the antiquity of man in the Victoria Cave is 

 solely due to the pcrfa-vidttm ingenium of Mr. Tiddeman. It 

 was first based on a fragment of fibula which ultimately turned 

 out to belong to a bear. Tlien it was shifted to the cuts on two 

 small bones." It is not, I believe, usual in the arena to hand 

 over your own broken disabled weapon to your adversary to 

 defend himself with when yoir take a new one. Vet this 

 appears to be one of Prof. Dawkins's tactics. Who, reading 

 the above remark, would believe that Prof. Dawkins ever held 

 the following opinion? " Although the fragment [of the fibula] 

 is vei-y small, its comparison with the abnormal specimen in 

 Prof Busk's possession removes all doubt from my mind as to 

 its having belonged to a man who was contemporary with the 

 cave hyena and the other Pleistocene animals found in the Cave " 

 (" Cave-Hunting," p. 120.) 



So far from the evidence having been "shifted" to the two 

 small bones, on the breaking down of the fibula evidence, the 

 latter event happened in 1878, whereas attention was called to 

 the former in the Reports for 1875-6, the respective years of 

 their discovery. 



2. "The bones are recent," says Prof. Dawkins. "This is 

 evidently a very old bone," said Prof. Busk, after inspecting and 

 experimenting on one of them submitted to him ; and the whole 

 of the circumstances of its discovery confirm that opinion. 



3. "The cuts have been probably made by a metallic edge." 

 That is a mere opinion, and to show what it is worth I may 

 remark that at the discus.sion at the Anthropological Institute in 

 1877, when Prof. Dawkins stated that the marks looked as if 

 they had been made with a Sheffield whittle, another member, 

 at least equally distinguished, and apparently equally desirous 

 to oppose the evidence, said that the marks seemed to have been 

 made by a rock slipping across the bones. 



4. Prof. Dawkins states that there were frequent slips of the 

 materials after I took charge of the work. He has, I think, been 

 misinformed, for his own visits to the Cave during that period 

 were not sufficiently frequent to warrant any such statement, 

 and our endeavour was to work the Cave in such a method as 

 would entirely prevent the possibility of such accidents and the 

 mixture of the remains. 



5. Prof. Dawkins goes on to .show: — (i) Either that Dr. 

 Geikie and I believe that "there is evidence of inter-glacial or 

 pre-glacial man, possessed of domestic animals, and probably 

 using edged tools of metals " (which we certainly do not) ; or 

 that (2) in his opinion goat has never existed anywhere save as 

 a domesticated animal, for his remarks proceed upon one or 

 other of these two assumptions. 



6. Bones of goat were far from uncommon in the hyena-bed 

 of the Cave, and found under such circumstances as would 

 render their slipping down from higher beds quite im- 

 possible. The same is the experience of that distinguished 

 explorer, M. E. Dupont, Director of the Geological Survey of 

 Belgium, in the caves uf that country : — " J'en maintiens absolu- 

 ment la co-existence avec ce^ especes perdues " (Joiini. Anthropol. 

 Inst., vol. vii. No. 2, p. 168). Unfortunately the non-existence 

 of goats in Pleistocene d posits in Great Britain has been 

 elevated to a dogma, and when the animals are found in such 

 association it is immediately assumed that they have slipped 

 from above — a confession to a very slipshod method of working 

 — or, that the beds have previously been disturbed. All such 

 cases should be most carefully inquired into and obser\'ed at the 

 time without prejudice. 



7. Again, Prof. Dawkins says that I wrote that the fact of the 

 finding of reindeer with the earlier Pleistocene animals was 

 "noteworthy," and that it is now too late to recall it. I do not 

 recall my statement, but I should like it quoted correctly. 

 " Your reporter had an impression that the reindeer remains 

 occurred at some height above the hyena-bed.' Be that as it 

 may, Prof. Dawkins's opinion- is entitled to grent weight, and 

 is indeed the view generally held. At the same time, consider- 

 ing that hyena and reindeer are not uncommonly found together 

 in caves, when, as in this case, we see them mixed together at 

 one or both ends of a section, but separated through an interval 

 of seventy feet in length by a thickness of deposits, w^ may 

 regard the fact as at least an interesting one, and, when found, 

 noteworthy" (Brit. Assoc. Reports, 1S76, p. llS). Prof. 

 Dawkins shall have the whole of that. I will not recall even 

 the middle sentence. R. H. TiDDEMAN 



Hastings, March 26 



^ This was also the opinion of Mr. Jackson, our painstaking superinten- 

 dent, who was daily at the Cave. 



^ i.e. , of the co-existence of these animals. 



