54 



SCIENCE. 



[Vol. VII., No. 154 



been subjected to very severe tests in Paris by 

 M. Hospitalier and other well-known electricians. 



The • juvenile lectures' at the Royal institution, 

 first rendered popular by Faraday in his ' Chem- 

 istry of a candle,' are this year being given by 

 Professor Dewar, who has chosen ' The story of a 

 meteorite ' as his subject. 



The Corporation of Liverpool has just issued the 

 programme of its twenty-first winter course of 

 lectures, to be given in the rotunda lecture-hall 

 of the Free public library. These lectures are 

 paid for by the corporation, and admission thereto 

 is absolutely free. The hall holds about six- 

 teen hundred, and is usually well filled by the 

 'great unwashed' of Liverpool, on Monday, Tues- 

 day, Wednesday, and Thursday of each week 

 from Jan. 4 to March 11. The first lecture is 

 by Mr. William Lant Carpenter, on ' Temperature 

 and life in the depths of the sea.' Prof. Oliver 

 Lodge, whose lecture on 'Dust' in Montreal will 

 be remembered, and several of his colleagues in 

 University college, Liverpool, as well as some of 

 the professors in Stonyhurst college, are among 

 the lecturers. It is greatly to be wished that other 

 towns, on both sides of the Atlantic, would 

 follow the example thus set. W. 



London, Dec. 23. 



LETTERS TO THE EDITOR. 



Correspondents are requested to be as brief as possible. The 

 writer's name is in all cases required as proof of good faith. 



Eskimo building-snow. 



I enclose a photograph, kindly sent me by General 

 Loring, of the Boston Museum of fine arts, of snow 

 impacted on a telegraph-pole, by a strong gale, near 

 the summit of Mount Washington. It furnishes a 

 good example, near home, of the texture of snow, 

 under the influence of a fierce wind and intense cold, 

 and will make clear some remarks I have previously 

 made in your journal regarding the use of snow 

 by the Eskimo among whom I travelled. In my 

 description of the igloo (snow-house) of the Innuit 

 in Science during the summer of 1883, I mentioned 

 that the first snows that fall are not used by the 

 Eskimo of my acquaintance to build snow-houses, 

 the preliminary igloos being of ice for three or four 

 weeks, until the deep drifts of snow had been sub- 

 jected to very low temperatures and the ' packing ' 

 influences of strong winds. The winter weather of 

 the summit of Mount Washington is in most respects 

 essentially arctic. 



In the accompanying illustration we see readily the 

 peculiar texture or strong 'binding' power of the 

 miow under those conditions of wind and cold, and it 

 is now in a condition for an igloo snow-block. It is 

 readily seen that it must, have great cohesion to hold 

 up such a heavy load on such a fragile support. 



The cohesion of snow in our latitudes (and the early 

 snow of the Arctic) is of a plastic, wet, or ' pasty ' 

 character, as shown in the making of snowballs, the 

 formation of huge balls of snow on the ground as 



they roll along, snowmen, balling on horses' feet, 

 etc. (also shown by Mr. Williams's letter in Science 

 of March 6, 1885 ; Mr. Stone's letter of May 29, 1885, 

 in Science ; and others to you). This is essentially 

 unfit for snow-building. 



The snow fit for igloos is of a dry, almost stone- 

 like character. The cutting of a thin portion from 

 the side of an arctic snow-block, instead of giving a 

 sheet of plastic snow as from a snowball, produces 

 a shower of fine powder, exactly the same as from a 

 large lump of loaf-sugar. In short, the arctic build- 

 ing snow-block stands in about the same relation to 

 those we would make here, as the brick just from the 

 mould, and before it is dried, bears to the same object 

 when burnt in the kiln, and ready for use. The arctic 

 snow-blocks ring like a well-burnt brick ; and this is 

 especially noticeable during intensely cold weather, 



HARDENED SNOW ON A MOUNT WASHINGTON 

 TELEGRAPH-POLE. 



when I have heard a snow-block, as it was struck 

 with a knife, give forth a clear, metallic, musical 

 sound, not unlike the striking of a highly tempered 

 bar of suspended steel with the hand, or other non- 

 metallic substance. 



I remember, when my natives were building a 

 snow-house on the high ' divide ' between Back's 

 Great Fish River and Hudson's Bay, the thermometer 

 in the minus GO's, a block of snow rolled down the 

 hill for fifteen or twenty feet, and I doubt if a rolling 

 guitar would have given forth many more confused 

 musical tones chan the bumping block as it struck 

 and bounded along down the hard, stone-like bank of 

 snow. 



Yet it must not be inferred that this dry, com- 

 pact snow has any of the characteristics of ice about 

 it. It is not only much lighter than ice, but, I be- 

 lieve, lighter than the plastic snow we have, certainly 

 not so dense as when made into the ordinary snow- 

 ball. In fact, the least quantity of ice in the snow — 

 which sometimes happens — renders it more or less 

 worthless for building, according to the amount. In 

 the late spring, banks of snow having southern ex- 

 posures, and thawing slightly about noon, only to 



