Mar. 9, iS88.] 



SCIENTIFIC NE\VS. 



237 



temperature than that of a flame, which is absolutely power- 

 less. A solid body penetrates easily through a viscid film of 

 air and instantly burns the paper, whereas a flame, even if 

 urged by a blast of air under heavy pressure, simply beats 

 against an elastic film of air, which transmits the heat slowly 

 through the paper to the vessel. My experiments tend to 

 prove that this adherent film disappears when the metal 

 reaches a high temperature, and from the average of a number 

 of results under different conditions, I come to the conclusion 

 that when the flame could be got into practical contact with 

 the metal its efficiency, area for area, was increased about six 

 times, other conditions being equal and the source of heat 

 being the same. The experiments were so complete and the 

 results so conclusive that, in the absence of unquestionable 

 proof to the contrary, the existence of a cold zone on the 

 surface of metal vessels containing water, must be taken as 

 an established fact. The existence of an adherent film of air 

 on the surface of all solid bodies does not necessitate the 

 upsetting of any present theories ; in fact, makers of baro- 

 meters and thermometers have to deal with this film as a 

 commercial difficulty and are fully aware of its existence. 

 Warrington. Thos. Fletcher. 



I am disposed to agree with Mr. Fletcher that a thin film of 

 air or gas (or perhaps a mixture of both) does exist between 

 the bottom of the metal vessel containing water and the flame 

 with which it is being heated underneath. Our slight differ- 

 ence of opinion is as to the cause of this intervening film. Mr. 

 Fletcher appears to think it is a " viscid or closely adherent 

 film of air," which somehow or other retains its position under 

 the bottom of the vessel and offers an impassable barrier to 

 the flame, whatever its temperature or force of impact. 

 Against this theory I would point out that as the film is not 

 enclosed, it would be physically impossible for it to resist 

 the impact of a flame driven agamst it with pressure. 



A more simple explanation, and doubtless a more correct 

 one, is that, owing to the low temperature of the metal vessel, 

 due to its containing water, flame does not actually come in 

 contact with it because the gases immediately under the 

 vessel cannot attain a sufficiently high temperature to produce 

 flame. If this is the case, it naturally follows that there will 

 always be a film of unburnt or partially burnt gas and air 

 between the flame and the vessel. 



Such a result is not observable if the metal vessel is empty, 

 and il is allowed to attain a high temperature — doubtless 

 because there is no longer anything to hinder the complete 

 oxidation of the gas and the production of flame in contact 

 with the heated vessel. If, on the other hand, we accept Mr. 

 Fletcher's explanation, how are we to explain the absence of 

 his " adherent film " of air when the vessel is hot enough to 

 promote the combustion of the gases in contact with it ? 



The Writer of the Article. 



VOLAPUK. 



In a conversation with some friends the other day on the 

 above linguistic convenience, and the general utility of an 

 international language, mention was made of the extra- 

 ordinary success which seems to mark the progress of the 

 Jews in certain commercial lines, and an attempt was made 

 to connect that success with the fact that most if not all of 

 the better-class Jews, no matter in what country they are 

 born and bred, learn Hebrew, and thus acquire a language 

 which enables them to communicate with their co-religionists 

 in aU parts of the world. Considering the comparative few- 

 ness of the Jews as a nation — about eight millions in all is, 

 I think, the present estimate, with about 60,000 in the 

 United Kingdom, and less than that number in France — the 

 number of well-known names supplied by the sect seems 

 striking enough to warrant some consideration and search 

 for the cause. The names of Disraeli, Gambetta, the Roths- 

 chflds, Bleichroders, Hirsch, Jessel, Montefiore, Sassoon, 

 Bernhardt, occur to me while writing, and the list could, of 

 course, be very largely extended with a little inquiry. In the 

 financial world they seem to practically reign supreme, and 

 SLS it is particularly in the cosmopolitan dealings connected 



with international finance that the value of an intermediary 

 language would be felt — thus enabling, for instance, a Jew 

 from Barbary to conduct a negotiation with his co-religionist 

 in England without the assistance of a third party as an in- 

 terpreter — it certainly seems that the possession of this 

 intermediary language is at any rate one important factor to be 

 taken into consideration in trying to account for the fact that 

 the Jews lead the van in international financial enterprise. 



I have no practical acquaintance as yet with Volapiik, and 

 so I am unable to pass any definite opinion on its merits ; 

 but I certainly agree with the spirit of the article in your 

 issue for 24th February, and think it does not need a prophet 

 to foresee a great stumbling-block to the diffusion of the 

 language, if its framers have arbitrarily selected the words 

 composing it, and have omitted to call to the aid of learners 

 the mnemonic advantages of basing their language on roots 

 common to the chief Aryan languages of Europe. Methyl. 



METEOROLOGICAL NOTES. 

 The severe weather of the last three winters, combined with 

 our similar experiences during the winters of 1878-9, 1S79-80, 

 1880-1, lead us to seriously question the theory put forward 

 some years ago by Mr. Glaisher, that our climate is getting 

 milder. It was asserted that the temperature of the year 

 had become two degrees warmer than it was 100 years ago, 

 and that the month of January showed a rise of no less than 

 three degrees. 



This conclusion is not borne out by a comparison of the 

 yearly temperatures at Greenwich since 1840. I have grouped 

 the forty-seven years elapsed during 1841-87 inclusive into 

 periods of about eight years each, and it will be noticed that 

 the last fifteen years of the series are colder than the mean of 

 the whole series : — 



Period. Mean Temperature. 



8yearsi84i-8 49^4 degs. 



8 years :849-56 49"o „ 



8 years 1857-64 49"45 1. 



8 years 1865-72 497 „ 



S years 1873-80 49'I ,, 



7 years 1881-87 49'l >> 



Mean of the 47 years = 49-3 degs. 

 The result found by Mr. Glaisher is probably to be attri- 

 buted to the facts that 100 year? ago Greenwich was far less 

 densely populated than now, and that the circumstances of 

 the observations have not been continuous, and therefore the 

 results are not strictly comparable during the long period 

 alluded to. 



Several references to the formation of hoar frost have been 

 made in the recent numbers of Scientific News. Hoar 

 frost is simply frozen dew or fog, and we find it chiefly de- 

 posited when there are no clouds and terrestrial radiation is 

 very profuse. With an overcast sky there is little evidence 

 of hoar frost. 



The value of the meteorological summary for 1887 printed 

 on page 141 of the current volume could be much enhanced 

 if " B. A. " gave his^/cza 0/ observation. It is always most 

 important to mention the locality in such cases. 



A Mejiber of the Liverpool Astronomical Society. 



INCIDENCE OF TECHNICAL EDUCATION. 

 In the article headed " The Struggle for Existence," Prof. 

 Huxley is quoted as saying, and that with justice, that "our 

 education rate is in fact a war tax, levied for purposes of de- 

 fence." Yet, with doubtful consistency, he contends that, 

 "for technical schools, the taxation should be local." Surely 

 every taxation for national defence should have a national 

 basis ! Justice. 



The Caucasus. — In addition to Elbruz, the culminating 

 point of the range, several peaks of the Caucasus are 

 now found to exceed 16,000 feet in height. Schkara and 

 Djanga are respectively 17,200 and 16,900 feet; Kosh- 

 tantan is 17,006, and Djchtan is 16,925. 



