j&thntift Jttuus 



FOR GENERAL READERS. 



Vol. II. 



SEPTEMBER 28, 1888. 



No. 13. 



PAGE 



Scientific Table Talk ... 329 



Gaseous FutI. (Illus.) 330 



The Volcanic Eruplion in Japan. 



(Il'Us.) 332 



Museums and their Arrangement ... 334 



General Notes ... ... ... ... 335 



Surface Tension. (Illus.) 337 



Exploration in Morocco ... ... 338 



Notes on Essential Oils 33S 



Natural Historv — 



The Protopteri. (Illus) 339 



CONTENTS. 



A New Parasite 



Cuckoo Hatching her Eggs... 



Miscellaneous Notes 



The Kagu. — II. 

 Domesticity in Animals 

 Reviews — 



English Worthies 



Journal of the Franklin Institute 

 Customs of Savage Races 

 International Geological Congress 

 Technical Education Notes 



TAC.V 







PAOB 



34° 



Abstracts of Papers, etc. — 







340 



Liverpool Science Club 



... 



3S« 



340 



Andersonian Naturalists' Socie 



ly ... 



3Si 



341 



The Leeds Naturalists' Club 





3S' 



342 



Physical Society of Glasgow 



Uni- 







versity 



... 



35" 



343 



Sales 





3S2 



343 



Exchanges 





35* 



344 



Selected Books ... 



... 



35* 



345 



Notices ... 





352 



35° 



Meteorological Returns 





352 



SCIENTIFIC TABLE TALK. 



By W. Mattieu Williams, F.R.A.S., F.C.S. 



Nearly allied to the glacier tables described in my 

 last are the glacier cones, but their history is rather 

 more complex and very interesting. The glacial ice 

 river is a paradoxer, some of its doings contradicting 

 point blank the orthodox proceedings that are predicated 

 as those of ordinary rivers. Thus on the glacier heavy 

 masses float and even rise above the general level, while 

 such filmy trifles as a fallen leaf or dead butterfly sinks to 

 considerable depth, because it is filmy. 



A dead butterfly falling on a glacier digs its own 

 grave, and then raises a monument to its own memory, 

 the height of such monuments varying from 6 to 8 

 inches to 6 and 8 feet, with about the same diameter at 

 the base. 



But what have butterflies to do on glaciers ? the 

 reader will ask. The answer is that their business there 

 is simply to die. They are carried by the wind from the 

 fields and gardens below, are killed by the cold, and fall 

 upon the ice. They are even found on the neve far above 

 the glacier. When I ascended Mont Blanc, two were found 

 on the Grand Plateau at an elevation of about 12,000 

 feet, and were kept as memorials of the ascent by the 

 junior guides who found them. They are commonly 

 found in making such ascents. 



Most of my readers will remember Franklin's cele- 

 brated experiment of placing pieces of cloth upon snow 

 exposed to winter sunshine, how they thawed the ice 

 beneath and sunk to depths varying with their colours. 

 The loose superficial structure of a butterfly coated with 

 microscopic feather scales is a remarkably good absorber 

 of radiant heat, and being exposed to the summer sunshine 

 acquires a high temperature. 



As the heat thus absorbed readily passes through so 

 thin a film as the butterfly's outspread wings, the ice 

 below them is more rapidly thawed than that of the less 

 absorbent naked ice around, and thus a hollow is formed 

 under the butterfly, into which it sinks, while heavy 

 masses of rock protect the ice below them and, as 

 already explained, stand above the general level on 

 moraines and ice cones. 



Let us now consider how the butterfly sinks, and the 

 necessary consequences that follow such sinking. On 

 a glacier with so little slope as the Unteraar the hollow 

 under the butterfly remains filled with water, and the 

 butterfly rests lightly on the bottom of this little pool. The 

 thawing action continues as at first, so long as the depth 

 is small enough for the radiant heat to pass effectively 

 through the water. 



After this another and very different action com- 

 mences. The temperature of water in contact with ice 

 is 32 Fah. When raised any temperature between 

 32 and a fraction above 39?, its density increases 

 proportionately, and therefore the water thus warmed 

 will sink below other water remaining at 32 . 



The watery grave of the butterfly when exposed to 

 the rays of the summer sun is superficially warmed, but 

 immediately the temperature of the surface water ex- 

 ceeds 32 , it sinks, and cooler water rises to take its 

 place. The warmer water in its downward course 

 strikes and thaws the ice walls and bottom of the grave, 

 and thus continually digs it wider and wider and 

 deeper and deeper, but this widening and deepening 

 does not occur equally on all sides. The south wall of 

 the grave is in shadow from about 6 a.m. to about 

 6 p.m., most deeply so at midday, when the sun is 

 working the most effectively. The solar grave-digging is 

 therefore the most vigorously conducted on the north 

 side of the excavation, both as regards walls and bottom. 

 It is thus elongated northwards, and deepened on the 

 north side. This proceeds to such an extent that the 

 bottom of the grave becomes a rather steep incline, from 

 due north upwards to due south, in the direction of the 

 longer axis of the now elliptical pool. 



We were shown several of these in various stages of 

 development. Into those that were far advanced we 

 thrust our alpenstocks, which, after a little preliminary 

 reeling, stood aslant, pointing due south with remarkable 

 accuracy, and also pointing upwards with a respectable 

 approximation to sun's meridian attitude at the place and 

 season. This is easily understood when we reflect upon 

 the action above described. The stick falls to the lowest 

 point it can attain ; in doing so its lower part occupies 

 the deepest end of the elliptical pool, and it leans against 



