66 



SCIENCE. 



[Vol. XVI. No. 391 



Portland, Me., which indicates the total pressure to the top of the 

 atmosphere, is 29.93 inches in January, and 29.81 inches in July, 

 therefore the pressure at Mount Washington must be .12 of an 

 inch lower in July than in January. This would be vicious rea- 

 soning, however, because we have ignored the fact that it is 

 warmer in July than in January, and consequently there is more 

 air above the mountain in the former month. It we put the 

 question to nature, we shall find that the pressure, instead of 

 being less in July, is actually half an inch more on the mountain. 

 We might at once conclude that there is a reversal of the usual 

 conditions, and that instead of having high pressure with low 

 temperature, and vice versa, as we are accustomed to note at the 

 earth's surface, we have on the mountain high pressure with high 

 temperatare, and vice versa, and extend our theory to storms and 

 high areas. It seems to me this would again be very vicious 

 reasoning: in fact, since there is a reversal of the law of press- 

 ures between sea-level and at some height, it would be impos- 

 sible to connect directly the fluctuations of temperature and press- 

 ure at the two situations. May we not consider that when a 

 storm approaches a station at sealevel it brings with it a high 

 temperature, owing to the south winds that blow toward it, and 

 that this high temperature must extend to a great elevation in the 

 atmosphere ? In other words, why may we not study tempera- 

 ture conditions without considering the pressure at all ? We find 

 that in a storm the temperature may rise twenty to thirty degrees 

 at the earth. Let us take out all the cases in which there is a 

 marked rise and fall in temperature at sea-level, say ten degrees 

 in two days, and determine the conditions at the height of Mount 

 Washington for the same days. In the following table I have 

 taken out the temperature at the maximum and minimum points 

 at Burlington, Vt., during the months October, November, and 

 December, 1873, and January, Februai-y, and March, 1874, and 

 also the temperature for the three days before and after these 

 points. The corresponding temperature for exactly the same 

 dates at Mount Washington (6,279 feet) were taken out. There 

 were found twenty cases at the maximum point, and the same 

 number at the minimum. The mean of each ten of these cases is 

 given in the table . 



These results agree for each ten days, and show, that, when 

 there is a rise of about nineteen degrees before a storm at sea- 

 level, there is a corresponding rise of about fourteen degrees at 

 Mount Washington; and a fall after the storm at the earth of 

 about fourteen degrees corresponds to a fall of about twelve de- 

 grees on the mountain. The same results in an opposite direction 

 are still more prominent on the approach and advance of a high 

 area. These results are strictly in accord with the teachings of 

 the most prominent meteorologists, and it seems probable that 

 these teachings must stand against all adverse criticisms. It is 

 very remarkable that so self-evident a truth as that a storm brings 

 with it an increased temperature to a very great height has been 

 sharply assailed in certain quarters. The facts are certainly 

 strongly against these new views, and we must conclude that they 

 could not be sustained for a moment except by ignoring the axiom 

 laid down at the beginning of this discussion. H. A. Hazen. 



Washington, D.C., July 28. 



A Scintillating Meteor. 

 On Saturday, July 19, at 8.52 p.m., I saw a meteor in the eastern 

 sky, passing through an arc of about thirty degrees in a nearly 

 horizontal direction, at a height of twenty-one degrees above the 

 horizon. Its course was from the south to the north; and I esti- 

 mate the time during which it was visible as three seconds, rather 

 less than more. The point where its path ended was almost due 

 east. The light it produced was as bright as that of a common 

 arc-lamp at a distance of some two hundred or three hundred feet. 

 There was no sound or other marked indication of a final explo- 

 sion, but there was a succession of sparks or scintillations during 

 the latter half of its path. A luminous streak, as usual, marked 

 the path for some little time after. J. A. Udden. 



Augustana College, Rock Island, 111 , July 21. 



BOOK-EEVIEWS. 

 Elementary Physics. By Mark R. Wright. London and New 

 York, Longmans, Green, & Co. 12°. 80 cents. 



The author of this text-book is head master of the Higher Grade 

 School, Gateshead, England. The book is suited for use in our 

 high schools and academies, and should be examined by those 

 looking for such a work. The plan is, by experiments which can 

 be performed with apparatus readily constructed, to make the 

 student familiar with the facts of physical science, little attention 

 being given to the theories. This plan will doubtless lead to good 

 results ; but it is singular to note how much the theoretical con- 

 siderations assist in co-ordinating the facts in physical science. It 

 even appears that in the past, on account of defects in theory, most 

 careful and acute observers have sometimes been obtuse in recog- 

 nizing what the facts really were. The book covers heat, sound, 

 light, magnetism, and electricity, and is to be commended to 

 American teachers. 

 Heat as a Form of Energy. By Robert H. Thurston, Boston 



and New York, Houghton, Mifflin, & Co. 12°. $1.25. 



One of the influences which for the past hundred years has 

 been helping along civilization has been that exerted by the em- 

 ployment of heat to do some of the world's rough work. As long 

 as man used only wind-power or water-power to do his sawing or 

 grinding for him, the question of energy — of capacity for doing 

 work — could hardly be a very complicated one. That the motion 

 of the wind-mill must be taken from the motion of the wind 

 niight be suspected, and so with the motion of the water-wheel ; 

 but when Watt and others had hitched a fire so as to turn a wheel, 

 it began to dawn on philosophers that there was something in this 

 phenomenon that called for explanation. It was soon found by 

 Rumford and his followers that the capacity of heat for doing 

 work was limited ; i.e., that there is a mechanical equivalent of 

 heat. But it was reserved for the students of the latter half of 

 this century to show what are the essentials for the conversion of 

 heat into work, and wherein it was possible to improve the steam- 

 engine so as to prevent, as far as may be, the losses which have 

 taken place in the past. 



AU this history of the development of the theory of the conver- 

 sion of heat into work is traced in Thurston's book now before us. 



Our author goes further, and tells us in plain language the 

 nature of that newer form of heat engine, the gas-engine, which 

 is now attracting so much attention, and shows us what the advan- 

 tages and disadvantages of this machine are. 



What the future may have in store our author does not venture 

 to predict, but he draws attention to the evidence we have of the 

 direct conversion in nature of oxidation processes into electricity, 

 which processes may be imitated by man in due time, with the 

 result of a more economic production of electricity than is now 

 possible. When this shall be, it can readily be understood that 

 electric prime motors would be a possibility. 



Our readers will know that Professor Thurston is the distin- 

 guished head of Sibley College of Cornell University, — a college 

 which is in the very front rank of the schools of mechanical en- 

 gineering, and will deem his clear exposition of the important 

 subject of " Heat as a Form of Energy" as of especial interest in 

 these days when the engines of the ocean greyhounds are so fre- 

 quently astounding the world with their performances. 



