♦ KNOWLEDGE ♦ 



[Seit. 4, 1885. 



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."—Alfred Tenn 



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FINDING THE WAY AT SEA. 



[1900] -Sir. R. A. Proctor, in his interesting article on " Finding 

 the Way at Sea," in Knowledge No. 199, Aug. 21, 1885, alludes to 

 an important danger in steering a ship— viz., that her compass may 

 seriously deviate on account of the presence of iron in her cargo. In 

 the St. James's Gazette of the same date an instance is quoted in 

 which the man at the helm found that he was unable to keep 

 his vessel in her course, and on an investigation being made the 

 irregularity of the compass which caused this difficulty was traced 

 to a passenger's umbrella, which was found to act as a very powerful 

 magnet, and, consequently, diverted the needle. 



In both these cases the cause of the variation is accounted for, 

 but I hope Mr. Proctor, or some of his correspondents, will be able 

 to give the raison d'etre for the following incident, which occurred 

 some years ago, when I went, one of a party of four or five persons, 

 from Algiers to Tunis by sea, on a steamer belonging to a French 

 Company :— One afternoon, about 4 p.m., we were steaming leisurely 

 along the North African coast, being at no time very far from the 

 shore, only keeping out a sufficient distance to avoid the various 

 ieadlands which jut out into the sea. It was towards the latter 

 half of the month of April ; we had a deep blue sky and lovely sun- 

 shine over head ; the sea was as unruffled as a lake. As we passed 

 a point where some of the higher ranges of the Atl is mountains 

 were visible, the aspect of the heavens in that direction was black 

 and threatening. Presently we heard distant thunder, and saw vivid 

 flashes of lightning over these ranges, but our own surroundings 

 remained as before. 



Shortly after, the captain came round to all the passengers in 

 turn, requesting the loan of any compasses which they might 

 possess, for he said his own (and he had several) had all gone 

 wrong. Our party between them produced two or three, and otlKT.-; 

 were also given to the officer by various passengers : but they all 

 exhibited the same unwonted variation, and continued to do so as 

 long as the storm lasted, or until we got out of its influence, when 

 they returned to their normal condition. The captain said after- 

 wards that it was most fortunate that this circumstance had 

 happened by daylight, for had it been dark he must have laid to, 

 as he could not have been sure of his course. Cosmopolitan. 



THE PHILOSOPHY OF CLOTHING. 

 [1901]— In his fifteenth article on this subject in Knowledge 

 (No. 199, August 21, 1?85). Mr. Mattieu Williams speaks of the 

 desirability that down should be more generally used than at 

 present, and of its great value in the manufacture of clothing. He 

 suggests the possibility of "carding and weaving the filaments 

 of feather down, such as common duck and goose down, swan's 

 down," &c. This is by no moans a lost art, for in Kashmir and in 

 Ladakli, or Western Tibet, which are countries adjoining Central 

 Asia (whence our remote ancestors probably came), a material is 

 woven called pushmina, made from the winter unde: -;oat of various 

 animals, chiefly that of the goat, the bara-singh (a kind of red deer), 

 nnd the ibex ; the dog also has it in those regions. In texture, push- 

 mina resembles the downy portion of the feathers of a bird, its staple 

 is short, perhaps not more than an inch to an inch and a-half in 

 length (rather less than more). The name of this down is pushm, it is 

 jnade into cloth of the finest kind, and is exquisitely soft, pleasant 

 wear, if it be the genuine article, and no Lilerties have been taken 



; the 





country. Tl.ei 

 extremely rare, for the dowi 

 is only collected by the nat 

 and at ven- great elevation 

 this aniuuil finds its wint 

 against the rocks ; the sliik; 

 morsel they find, but it ma 



to wind round the hat, tui. ; 

 require to be about four ■ r 



with other .«ul stances. It w. 

 catch a few Kashmiris and g 

 paring the fibre. 



GREASY DUCKS. 



, not by writing. I simply deny, positive 

 nac ani- of the feathers of these animals ai^ 

 o ducks rather than Huxleys for i)roof. 

 uthorities against me; so much the worse fur 

 much the lietter for me : he simply pro\es t ! 



waterprooting and falls bnrk upon t 

 greased part," this being always out of 

 tips up, with head immersed, in search of food below. 



W. Mattieu W 



August 7tli, p. liio, he 

 " over all parts of the 

 ives up the greasy breast 

 st in need of the alleged 

 root of the tail as the 

 when the duck 



STARLIGHT. 



[1903]— I am delighted to fird that my idea that the light of a 

 moonless night does not come from the stars is established. (At 

 the same time it is surely rather hard on Mr. Madge to say it exists 

 only in his imagination, for it is the universal belief among men 

 — saving those better informed — " a fine starlight night.") 



I believe that our air is lumicous for this reason :— Given two 

 equally cloudy skies, one with high barometer— therefore high 

 clouds, the other with low clouds, the twilight (daylight also, pro- 

 bably, but not so obviously) will be much longer and brighter in 

 the first case than in the second. Now, the clouds cutting off all 

 "ight, ah e:ctra, it appears that the thicker the earthwi 



of air the ; 



■r the ill 



The keen observer of " Wild Life ia a Southern County " writes 

 (xlii.) : — " I have myself been often much interested in the remark- 

 ible difference of the degree of darkness when there has been D' 





There ai 



.Ithongh the sky be clear of visible 

 le stars are shining, it is, iu familiar phrase, " as black 

 The sky itself is black between the stars, and they do 

 not seem to give the slightest illumination. On the other hand, 

 there are nights without a moon, when it is (though winter time) 

 quite light. Hedges and trees are plainly visible; the road is 

 light, and anything approaching can be seen at some distance ; and 

 this occasionally happens though the sky be partly clouded. So 

 that the character of the night seems rot to depend entirely upon 

 the moon or stars. The shepherds on the hills say that now and 

 then there comes an intense blackness at night which frightens 

 the sheep and makes them leap the hurdles." 



In all my life there is one particular night which stands out as 

 the blackest— June 4, If 54. I had to walk home through Bedford, 

 and if I had not known it well enough to do it blindfolded I should 

 really have been obliged to grope my way along the streets. This, 

 too, was in the period of " no real night." 



It may be said, " If the air is luminous why isnot a shut-np room 

 at night as light as when the shatters are left open ? " Probably 



enclosed is 



- small. 



The popular proverb says, " The darkest hour is just before 

 dawn." If that is true one might conclude that the luminosity of 

 the air is due to the past sunshine, and is hourly decreasing. This 



not that the moon and the aurora would introduce new elements 

 into the problem. Halltaeds. 



