460 



NA TURE 



[Oct. 3, 1872 



second (lame being ignited, the temperature rises to ea'-SS, thus 

 increasing the differential temperature to 2°'SS. 'l"he ignition of 

 the third flame augments the differential temperature to 3''So. 

 The remaining llamc-i being ignited in regular order downwards, 

 their combined radiant energy elevates the temperature to 67"'90. 

 Deducting the temperature of the enclosure c (60°), the trial 

 shows that although the single flame at the maximum distance 

 from the bulb, is capable of producing a differential temperature 

 of i°'76, the energy of the ten flames together produces only 

 7°'90. This fact furnishes conclusive evidence of the imperfect 

 transparency of the flames. Assuming that the heat rays are 

 capable of passing freely through the incandescent medium, it 

 will be perceived that the entire series of flames should produce 

 a differential temperatue of I •76X 10= 1 7^ '60, showing a retarda- 

 tion of I7'6— 7'9.^ 9^"7. And if we take into account the 

 diminished distance of the lower flames from the bulb of the 

 thermometer, it will be found that the actual retardation greatly 

 exceeds this computation. We have tlius demonstrated tliat 

 flames are most transparent, as supposed by Pore Seechi. Con- 

 sequently, the inferences drawn from the experiment to which 

 the distinguished savaii refers in his letter to the French Academy 

 of Sciences are wholly unwarrantable. 



Having disposed of the question of transparency, and ascer- 

 tained the degree of temperature communicated to the thermo- 

 meter by the radiant energy of the flames alone, let us now 

 suppose that the instrument has been turned towards the sun. 

 The temperature produced by the combined energy of solar 

 radiation, and the radiation of the flames, after directing the in- 

 strument towards the luminary, will be found recorded in the 

 fifth column of the table. Our space not admitting of a detailed 

 statement, we must dispense with an examination of the energy 

 transmitted for each flame separately, and at once consider the 

 effect produced by passing the sun's rays through the entire series. 

 It has already been stated that the radiation of all the fl.imes 

 combine 1 imparls a differential temperature of 7"'90 to the 

 thermometer. By reference to the table it will be seen that, the 

 temoeratnre produced by the sun's rays is 21" '69 when the flames 

 are extinguished.* Consequently the temperature, after lighting 

 the whole series, ought to be 2 1 '69 + 7 'go = 29°' 59, since solar 

 heat, under analogous conditions, is capable of increasing defi- 

 nitely the temperature of substances whatever be their previous 

 intensity, t Referring again to the table, it will be found that 



* No.witlislandjng tlie low temperatnl-e indicated l>y the thennometerof the 

 experimental apparatus, si'-Gg, the actupt solar intensity during the iovesti- 

 gation, ascertained by the actinometer, has at no time Ijeen less ttian 50°, a 

 very instructive fact proving the futiiity of attempting to measure solar in- 

 tensity by thermometers the bulbs of which are exposed to the refrigerative 

 action of surrounding air. For the purpose in view, hov/ever, tfiat of measur- 

 ing the comparative radiant power of Hames and solar fieat, the unavoidable 

 exposure of the bulb to atmo,^pheric influence, is unimportant, provided the 

 enclosure be kept at a constant temperature during the experiments. 



t Pere Seechi reminds us, in " Le Solcil," that Mr. Waterston found by his 

 solar intensity apparatus, that, when the thermometer was enclosed in a 

 heated vessel imparting upwards of 400" Fah. to the bulb, the same degree of 

 ditTerential temperature was rc.iched by exposure to the sun, as when a cold 

 enclosure was employed wliich reduced the indication of the enclosed ther- 

 mometer to that of ordinary atmospheric temperature. 



the maximum increase of temperature attending the passage of 

 the comparatively cold solar rays through the incandescent gas, 

 is 2" -3 1, while the radiant energy of the flames produces a 

 differential tenqieratureof 7°-90. This extraordinary discrepincy 

 points to an increase of molecular energy within llie incan- 

 descent gas, notwithstanding its temjierature being fully 1,900" 

 higher than that [iroduced by the sun's radiant hea*. 



J. Ericsson 



NOTES 



Mr. DAitvviN's forthcoming work on "Expression in Man 

 and Animals " bids fair to be of a more popular character than 

 any of his other publications. It will commence with a statement 

 of the general principle of Expression ; — that serviceable actions 

 become habitual in association with certain states of the mind, 

 and are performed, whether or not of service, in each particular 

 case. This will be illustrated in the case of expression of the 

 various emotions in man and the lower animals. The means of 

 expression in animals will then be discussed, and the special ex- 

 pressions of animals and man, such as the depression of the cor- 

 ners of the mouth in grief, frowning, the firm closure of the 

 mouth to express determination, gestures of contempt, the dila- 

 tation of the pupils from terror, the causes of blushing, &c. In 

 conclusion, the bearing of the subject will be spoken of on the 

 specific unity of tlie races of man, the part will be discussed which 

 the will and intention have played in the acquirement of various 

 expressions, and the question of their acquisition by the progeni- 

 tors of man will be referred to. Seven heliotype plates repro- 

 duced from photographs will illustrate the work. 



History is said to repeat itself. It is singular to find that 

 six months ago the colony of Victoria was involve^I in a similar 

 controversy to that which has recently agitated the sc'entific 

 world at home. Baron Friedrich von Mueller is the Dr. Hooker 

 of Australia. The Botanic Gardens at Melbourne have become 

 under his management as truly scientific an institution as those 

 at Kew, and their Director has performed similar eminent services 

 both to the colony and to the mother country in spreading a 

 knowledge of the value of the indigenous vegetable products of 

 Australia. After twenty years' service, however, it is discovered 

 that von Mueller is "not a landscape gardener," and an agita- 

 tion is set on fool — we do not, however, hear that it originates 

 in the Board of Works, if there is such a department in 

 Victo ria, nor do we know who is the Ayrton of the An- 

 tipodes — to deprive hitn virtually of the control of the Botanie 

 Gardens. Next to the removal of Dr. Hooker from Kew, 

 botanical science all over the world could receive no severer blow 

 than the deposition of von Mueller from the position he occu- 

 pies at Melbourne. 



We believe that, in addition to the 4,000/. which we recently 

 noted, another S,ooo/. will be voted in the next Frenc'n Budget, 

 to be devoted to the preparations necessary for the observation 

 of the forthcoming Transit of Venus. 



The Californian Academy of Sciences experienced a genuine 

 sensation at its meeting on September 9, in welcommg Prof. 

 Agassiz returning from the Ilasskr Expedition, on his first 

 arrival on United States' territory, where he was received by 

 Prof. Davidson, the president of the Academy ; Prof. Gillman, 

 the principal of the University of California, Prof. Torrey, of 

 Columbia, the Nestor of American Botanists, and others. In 

 his address on the occasion, Agassiz alluded in the following 

 terms to the growth beneath his eyes of the great Cambridge 

 Museum: — "I went single-handed to Cambridge, to teach 

 natural history, twenty-five years ago. When I delivered my 

 first lecture there was not in the University a single specimen 

 which I could use to illustrate what I had to say. And yet a 

 little band of students, fe?ling an inte.est in what they coul.l learn 



