8 2 



NA TURE 



[Nov. 27, 1884 



and on those so shallow as to freeze to the bottom, that when 

 the winter ice had nearly all thawed away, the remaining ice 

 assumed the basaltic or columnar form, which on the deep-water 

 lake could be walked over with perfect safety in the early.morning, 

 being then perhaps six or eight inches thick, and apparently 

 quite solid, but which all disappeared a few hours afterwards in 

 a magical manner, the columns having become very rapidly 

 detached, especially if there was a fresh breeze, and, falling 

 over on their sides, became invisible, and drifted to the lee side 

 of the lake. This often led to a very general but wholly 

 erroneous belief that the ice had sun/;. 



The question may be very naturally put : What has all this 

 to do with "peculiar ice forms " on dry land ? 



The foregoing particulars are mentioned to show that ice in 

 wasting away assumes not unfrequently the basaltic form. 



I believe that the bank on which the peculiar ice was noticed 

 by Mr. Smith, and described by him as bare of vegetation, is 

 usually covered in winter by a deep snowdrift, and that, towards 

 spring and later, pressure and the percolation of water from the 

 thawing surface converts the lower stratum of snow— still 

 colder than the freezing point — into ice. May not this ice, 

 when nearly all wasted away, assume, as it does on the lakes, a 

 basaltic structure ? 



May not the division of this four inches of ice "into four dis- 

 tinct layers— the columns of one layer being readily detached 

 from those underneath " — be accounted for by what I have found 

 to take place in snowdrifts, as I shall attempt to explain. 



In building snow-huts there are two requisites essential for 

 perfection in this kind of architecture. First, the snow has to 

 be packed so firmly by the force of the wind as to be hard 

 enough to walk over without sinking in it ; secondly, the required 

 depth of from fifteen to sixteen inches must be the formation of 

 one and the same snowstorm and gale of wind. If this is not 

 so, and the required depth of fifteen inches has been the result 

 of three separate snowstorms, the blocks of snow, when sawn 

 out, would not cohere, but break into three narrow strips of four 

 or five inches each, which would render hut-building in the proper 

 artistic manner and with rapidity (an important point in very cold 

 weather) impossible. 



_ These separate layers of ice noticed by Mr. Smith may pos- 

 sibly be the small remains of four separate and distinct snow- 

 storms piled one above the other, which I know do— whilst in 

 the form of snow— retain their individuality for the whole winter, 

 although super-imposed the one upon the other. 



The layer of "dirt " which Mr. Smith, from his point of view, 

 very naturally supposes to be evidence that the mass of" pe< uliar 

 ice "was pushed up from below, may be very easily otherwise 

 accounted for. 



In all gales with drifting snow in the Arctic, especially when 

 there are high steep lands to be passed over, part of the ground 

 is cut away by the driving snow in the form of fine powder or 

 dust, and is carried sometimes a long way until deposited with 

 the snow in some sheltered part. 



This dust is small in quantity as compared with the bulk of 

 snow, and is scarcely discernible when mingled with it ; but when 

 greater part of the snow melts, the dust shows as a very percept- 

 ible coat of "dirt" on the surface, which I consider has come 

 down from above instead of being "pushed up from below" 

 out of the ground as Mr. Smith believes to be the case. 



4, Addison Gardens, Kensington, W. John Rae 



Fly-Maggots Feeding on Caterpillars 

 In reply to Dr. Bonavia's note on the above subject in 

 Nature for November 13 (p. 29), I beg to inform him that 

 the larva; of the house-fly are often internally parasitic on the 

 larvae of Lepidoptera. I have bred them in large numbers from 

 Vanessaio and Saturnia carpini, also from other species more 

 sparingly. Nor is this the only species of Diptera that infests 

 Lepidoptera. p. N. Pierce 



143, Smithdown Lane, Liverpool 



Birds-Nest Soup 

 IN Nature of July 17 last (vol. xxx. p. 271), just received, 

 appears an article on " Birds'- Nesl Soup," which contains the 

 statement that " the , nests of the bats 1 and swifts were sun 

 hanging in clusters from the sides and roof." That the addition 

 of the "bats " to the contributors of the nests is not an acci- 

 1 The italics are mine.— E. T . L. 



dental lapsus calami is shown further on, when we read that the 

 visitor eating the soup will "at any rate have the satisfaction of 

 knowing that he has before him a dish the principal ingredient 

 of which was formed by the little swifts and bats ' which inhabit 

 the Gomanton Caves," &c, &c. 



I too have visited caves from which large quantities of edible 

 birds' nests w^ere collected. I saw plenty of bats, but, unfor- 

 tunately, none of their nests ! The nests / saw were built by 

 a " swiftlet " (Collocalia, Gray), and were more or less the 

 product of their ozvn salaatory glands. This fact was known as 

 far back as 1 781, over one hundred years ago ! ! The "while 

 nests " are supplied entirely by the inspissated saliva of the bird, 

 and are the first produced. These are taken, and sold for their 

 weight in silver. The next made by the birds are mixed with 

 rootlets, grasses, &c, and often show traces of blood, from the 

 efforts of the birds to produce the saliva. These are esteemed 

 second quality. The third nest is composed of extraneous sub- 

 stances cemented together and to the rock with a little saliva ; 

 these are generally left for the bird to breed in, and are usually 

 destroyed at the end of the season to compel the birds to build 

 fresh white ones after their powers are recruited by a year's rest 

 and stimulated by the breeding " storge." 



All this genus — the swiftlets [Collocalia) — wherever found, 

 produce, in a greater or less degree, an amount of saliva which 

 is used in building their nests and attaching them to the surfaces 

 of rocks or the insides of hollow trees and leaves. The proper- 

 ties in this saliva— as in the kava of the Fijians and the pep sine 

 of the calf — give it its value in the eyes of the Chinese. If it 

 were simply a " fungoid growth" woven together, why is it not 

 gathered from the limestone rock in its pure state? 



British Consulate, September 17 E. L. La YARD 



THE PRIME MERIDIAN CONFERENCE 

 AX7'E believe that the protocols of this Conference have 

 v * not yet reached this country. In the meantime we 

 are permitted to give the official statement of the reso- 

 lutions. 



Final Act 

 The President of the United States of America, in 

 pursuance of a special provision of Congress, having 

 extended to the Governments of all nations in diplomatic 

 relations with his own, an invitation to send Delegates to 

 meet Delegates from the United States in the City of 

 Washington on October 1, 1884, for the purpose of dis- 

 cussing, and, if possible, fixing upon a meridian proper to 

 be employed as a common zero of longitude and standard 

 of time-reckoning throughout the world, this International 

 Meridian Conference did assemble at the time and place 

 designated ; and, after careful and patient discussion, has 

 passed the following resolutions : — 



I. " Resolved, That it is the opinion of this Conference 

 that it is desirable to adopt a single prime meridian for 

 all nations, in place of the multiplicity of initial meridians 

 which now exist." 



This resolution was unanimously adopted. 



II. "Resolved, That the Conference proposes to the 

 Governments here represented the adoption of the 

 meridian passing through the centre of the transit instru- 

 ment at the Observatory of Greenwich as the initial 

 meridian for longitude." 



The above resolution was adopted by the following 

 vote : — 



In the affirmative — 



Austria- H angary, M exico, 



Chili, Netherlands, 



Colombia, Paraguay, 



Costa Rica, Russia, 



Germany, Salvador, 



( ireat Britain, Spain, 



Guatemala, Sweden, 



Hawaii, Switzerland, 



Italy, Turkc\ , 



Japan, United States, 



Liberia, Venezuela. 



