TUANSACTIONS OF SECTION A. 



657 



the priniiiry and separated from it l)v a space of about tlireo defrreos. It con>i-;t.s of 

 a ring of f,n'eoii succeeded on tlie iiij^ide by a v'nv^ of red li^lit, each beiiiy aljoiU luilf 

 ii degree in lireadtli and concentric witli the principal bow. I'lienoniena of ibis 

 kind came under my notice on the mornings of tlie I'l'nd and l'3rd .Septemljcr, 1802, 

 ;iud lllh July, l'^?(), in the neigbbourluiod of Kanlurii, in the county of ("ovk. On 

 smno of these occasions I remarked tliut the outer verge of the green ring was 

 liL'tliT defined than the inner verge of the red one. The latter was souietiuies 

 irregular, owing apparently to the presence of snniU needles or lines of grey or 

 whitish light crossing the arc. The appearances in eacli instance were visible for 

 nearly an hour. 



Having some time ago searclied through various scientilic periodicals up to the 

 vear 188U, I found therein only two instances in which corrrspouiling phenomena 

 had been recorded, one of which is in the description of a lunar fogbow seen olf 

 tlie coast of California, in LStiO, by Lieut. J. M. (lillis, of the American Navy ; in 

 this no colours Avere observed ('American Jmirnal of Science,' vol. xxx. p. uO'i). 

 The otlirr description referred to is contained in Col. Sykes' ]iaj'.ev 'On the 

 Atnid.-plieric Tides and ^leteorology of the Deccan," where In- says: ' IJnder ;• cdui- 

 hination of favourable circumstances, it (the circular vainbow) apjieared (^uite pe-fect 

 'if (he most vivid colours, one half above tlio level on which I stood, the other half 

 helow it. * • "* The brilliant circle was accompanied by the usual outer bow 

 in fainter colours ' (' I'iiilosophicarJ'ransrictions for 1S;!5,']1. l'J3). In this instance 

 it aj.pears jiossible t!iat the inner bow wiiich he describes as a " brilliant circle" 

 was exceeded in brilliancy by the outer bow, notwithstanding the statement that 

 the latter appeared " in fainter colours ; ' for this nuiy have reference to t!i<! mixtuie 

 and consequent indistinctness of the colours, and not to the intensity uf the light. 

 Bearing in mind this aceo])tation, and leaving out the central ligures, Col. Sykes' 

 (Ifseription of the phenomena would seem to agree with that which 1 have above 

 given. 



.\s to the cause of the additional rings, it would fieem reasonable to regard them 

 as analogous to the ' interferimco bows,' which so fre'iuently appear in showers of 

 rain, were it not that on such a .-apposition (according to received ]n'inci])les) the 

 red colour ought, to be the tirst to re-ajijiear after evanescence, and should therefore 

 he outermost. IIow the gret'u conu'S to have that place instead, or \\hy the colours 

 appear se])arately in t! o additional bow though blended together in the primary 

 ai:d more brilliant one, is more than I have Iteen able to determiue. 



19. 



On iJie Temiicrdlnre of tho. Interior of o Bhch (f Mtltiuij Ice, 



Ihj JaMK.S E. FliANCld. 



Proceedings of the Royal 

 following description of an 



The jiaper by Professor James ]). Forbes in the 

 Society of lldinburgh for April I'J, 18GS, contains the 

 experiment by him : 



' Water being caref dly frozen into a cylinder several inches long, with the bulb 

 of thermometer in its axis, and the cylinder being then gradually tiuiwed,. or 

 allowed to lie for a considerable time in pounded ice at a thawing temperature, 

 showed also a temperature decidedly inferior to 152°, not less, I think, than 0'3ii° 

 Fahrenheit.' 



In this experiment it appears that the formation of ice on the bulb of the ther- 

 mometer may have acted upon it mechaincally and atlected the accuracy of tho 

 results. To avoid error from tb.i;; cause I procured a block of clear ice from 

 Merrimack Kiver^ and cut it to tit loosely into a cask, tho dimensions of the block 

 when litted being seventeen inches in diameter and sixteen inches high, the dia- 

 meter of the block of ice being about two inches less than that of the cask. The 

 space not occupied by the ice was tilled with water from the same river, allowing 

 the ice to float. A hole, one and three-fourths inches in diameter, and ten inches 

 deep, was bored in the axis of the block, and a cover of ice closely fitted to it. 



Two thermometers, No. 1 and No. 'J, of similar i'orm, by Seifort of Uoston, 

 were used. They had two bulbs with stems, about 3"2o inches long between them, 

 graduated from 20° to 35° Fahrenheit ; the length of a degree in No. 1 being 0'405 



1884. U u 



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