330 



SCIEJSTCE. 



[Vol. VII., No. 166 



flection, but only the radiated heat ; and the rate 

 with which the bulb, if spherical, would radiate heat, 

 would be to that with which it would receive and 

 absorb heat as yfi to i r' ^ , in which r is the relative 

 radiating power of the earth's surface. Hence for 

 the static temperature of the thermometer, that of 

 the earth's surface being supposed to be stationary, 

 we should have 



fjL 6 = i r' or - e" = 300 log 1 r. 



In case of a maximum radiating power of the 

 earth"s surface, in which case r — 1, we have 



e - e = - 300 log 1 = 300 X 0.301 = 90° C. 



for the difference between the temperature of the 

 earth's surface and that of the exposed thermome- 

 ter, the latter being the less. It is seen that the 

 difference is the same, whatever the temperature of 

 the earth's surface. According to this result, if the 

 temperature of the earth's surface were maintained at 

 0° C, that of the thermometer would be —90° C, if 

 the law of Dulong and Petit can be extended to so 

 low a temperature. 



If the earth's surface were polished silver, and of 

 the ordinary temperature, the temperature of the 

 thermometer would be nearly that of absolute zero. 

 If we suppose that the earth's atmosphere, when 

 clear, radiates and reflects back to the body four- 

 fifths as much heat as the body radiates into it, then 

 the enclosure, comprising the earth's surface on the 

 one side, and the atmosphere on the other, lacks one- 

 tenth of completeness, and we then have from the 

 preceding expression, 



d > _ e - _ 300 log 0.9 = 300 X 0.046 = 13.8° C. 



for the difference between the temperature of the 

 earth's surface and that of the thermometer, in case 

 the thermometer received no heat by convection 

 and conduction from the surrounding warmer air. 

 In the case of Melloni's cups, the former of these is 

 prevented, and hence the thermometer in these stands 

 at a lower temperature than one does suspended in 

 the open air, where the colder air immediately in con- 

 tact with the thermometer-bulb falls down, and 

 warmer air takes its place. 



Supposing the atmosphere and the earth's sur- 

 face to furnish nine-tenths of a complete enclosure 

 to a body near the surface, then, at an altitude 

 which leaves one-half of the atmosphere below it, 

 they would furnish something more than 0.7 of a com- 

 plete enclosure ; for the amount of heat escaping 

 into space is not quite proportional to the mass passed 

 through, especially in the case of dark heat. We 

 should have, in this case, 



e' - e < - 300 log 0.7, or 46.5° C, 



in case of no convection and conduction ; but these, 

 of course, would diminish the difference very much. 

 This result, in comparison with the preceding one, 

 explains the low temperatures of bodies at night, 

 when exposed in the air on high mountains a little 

 above the earth's surface, so as to receive no heat 

 from contact with the. surface. 



The greater the altitude,, the more nearly would 

 the difference approximate to 90° C, and would sensi- 

 bly reach it at a point leaving no sensible portion of 

 atmosphere above it, and even surpass it if the 

 point were so high as to sensibly diminish the sub- 

 tending solid angle. 



The whole of the earth's surface, of course, cools 



considerably during a clear night ; but this only con- 

 tinues until a temperature gradient is formed by 

 which heat is conducted from the lower strata to the 

 surface as fast as it is radiated into the atmosphere. 

 This state, however, can be only approximately 

 reached, and, if the night were continued, the cool- 

 ing would still go on ; but the rate of cooling be- 

 comes very small in the latter part of an ordinary 

 night, and much less in that of a polar night. 

 Bodies exposed in the open air, of course, receive 

 no sensible amount of heat by conduction of heat 

 through the air up to the bodies, and so their tem- 

 peratures fall much lower than that of the earth's 

 surface, and the differences are given by the pre- 

 ceding conditions. Wm. Ferrel. 



Maori poetry. 



An example of Maori poetry may be interesting to 

 some of your readers. The first is a modern Maori 

 love-song composed by a young native and sent to his 

 sweetheart. I am indebted to Mr. C. O. Davis of 

 Auckland, New Zealand, for the translations. 



At eventide I lay me down to rest, 



As winds from the great ocean pierce my frame. 



Come, ye soft northern air?, hasten your speed, 



"With messengers of love to me. O maiden ! 



Send me thy epistle to cheer this heart 



Of mine. — to dry the tears which freely flow 



For thee, O Rosa, absent from thee so long. 



When darkness has set in, I rest alone, 



The while I fancy thou art present, 



And all my thoughts are fettered by thy love. 



A maiden' 's lament on account of the desertion of her lover. 



Retire, O sun ! and leave the night to me. 



While tears, like water, from these eyes are flowing. 



The sound of footsteps is no longer heard, 



O Taratu ! thou comest not again 



By way of Waishipa's headlands ; still 



The sea-fowl show their breasts at Mitiwai, 



But my lover lingers in the north. 



Binding thyself to thy own landscapes there. 



Ah ! shall my days of weeping never cease ? 



C. F. Holder. 



Pasadena, Los Angeles county, Cal., 

 March 21. 



Names of the Canadian Rocky Mountain peaks. 



As to the naming of the Canadian Rocky Mountain 

 peaks, Mr. Ingersoll may withdraw his correction 

 made upon the authority of Dr. George M. Dawson. 

 Here is an extract from Douglas's journal, under 

 date of May 1, 1827, printed in companion to Botani- 

 cal magazine, ii. 136, in 1836. 



" This peak, the highest yet known in the northern 

 continent of America, I felt a sincere pleasure in 

 naming 'Mount Brown' in honor of Robert Brown, 

 Esq., the illustrious botanist, a man no less distin- 

 guished by the amiable qualities of his mind than by 

 his scientific attainments. A little to the southward 

 is one of nearly the same height, rising to a sharper 

 point : this I named ' Mount Hooker ' in honor of my 

 early patron the professor of botany in the Uni- 

 versity of Glasgow." 



Dr." Hector, "who in 1857-59 was attached to 

 Captain Palliser's expedition," may indeed have 

 named ' Mount Balfour,' curiously sandwiched be- 

 tween the names of Hooker and Brown. Douglas 

 could not well do that, the worthy Edinburgh pro- 

 fessor so honored being at that time a lad of nine- 

 teen. A. (i. 



