MISCELLANY. 



6 35 



of the ocean appears to depend upon the 

 depth of the superincumbent water. So 

 universally is this the case that the observ- 

 ers on board of the Challenger needed only 

 to know the depth at any locality in order 

 to foretell the character of mud that would 

 there be brought to the surface by the 

 dredging apparatus. According to Prof. 

 Thomson, " the mean maximum depth at 

 which the globigerina-ooze occurs is about 

 2,250 fathoms. The mean depth at which 

 we find the transition gray ooze is 2,400 

 fathoms, and the mean depth of the red-clay 

 soundings is about 2,700 fathoms." These 

 three sedimentary formations, however much 

 they differ from each other, are all the re- 

 sult of the precipitation to the bottom of 

 the dead shells of the globigerina and other 

 surface animals. Why, then, do they differ 

 so much in appearance and in chemical 

 constitution ? The globigerina-ooze is 98 

 per cent, carbonate of lime ; the gray ooze 

 consists of carbonate of lime with a greater 

 or less proportion of clay ; the red ooze is 

 almost pure clay, viz., silica, alumina, and 

 red oxide of iron. Prof. Thomson accounts 

 for the absence of carbonate of lime from 

 the red clay, and its partial absence from 

 the gray ooze, by the theory that at great 

 depths there is an excess of free carbonic 

 acid. This would convert the carbonate of 

 lime of the shells into a soluble compound. 

 In that case the red clay would be " the in- 

 soluble residue, the ash, as it were, of the 

 calcareous organisms which form the globi- 

 gerina-ooze after the calcareous matter has 

 been removed." It is worthy of note that 

 living animals, brought up by the dredge 

 from great depths, have their calcareous 

 shells very rudimentary. 



A Ballooning Spider. A paper of singu- 

 lar interest, by Dr. Lincecum, contributed 

 to the Smithsonian Institution and published 

 in the American Naturalist, describes the 

 marvelous art of the gossamer spider in the 

 construction and navigation of her aero- 

 nautical ships. In Texas, according to the 

 author, December is the month for these 

 ballooning spiders to emigrate. When they 

 intend to make an ascension, they fix them- 

 selves on some extreme point of the- branch 

 of a tree, or weed, or corn-tassel, then care- 

 fully spin out a lock of white gossamer, five 



or six inches long and two inches wide in 

 the middle, tapering toward the ends, hold- 

 ing it all the time in the gentle breeze by a 

 thread two or three inhces long, which, 

 being attached to the end of the selected 

 point, detains the balloon until it is finished. 

 They then spin out at the bow two lines, 

 thirty or forty feet in length, and another 

 of twenty or thirty feet at the stern, then 

 cut the cable and sail away on an inclined 

 plane. There are a mother and half a dozen 

 or more young spiders aboard every balloon, 

 and thus the species is scattered over vast 

 districts. These tiny aeronauts choose for 

 starting on their voyage a clear day, tem- 

 perature 60 Fahr., wind gently from the 

 south. At about 1 p. m. they may be seen 

 sailing with the wind. Toward 4 p. m. the 

 spectator will observe that the balloons are 

 beginning to descend. When the streamers 

 strike some tall weed or grass the air-ships 

 are made fast and the passengers instantly 

 leap out, spinning out a thread as they fall, 

 thus landing in safety. 



A Demand of Modern Edncation. In an 



address delivered on the occasion of the 

 dedication of Pardee Hall, the scientific 

 school attached to Lafayette College, Prof. 

 Rossiter W. Raymond made some timely re- 

 marks upon the absurdity of attempting to 

 complete a young man's aducation in the 

 same time now as fifty years ago. The 

 enormously-increased demands of modern 

 life, said Prof. Raymond, requiring as they 

 do that a man shall know more things, and 

 know how to do more things, than were 

 formerly sufficient for his reasonable suc- 

 cess, are not to be satisfied by a mere change 

 in a few subjects of instruction. It is not 

 enough to substitute one study for another. 

 The period of study must also be prolonged. 

 In recognition of this principle, while it is 

 for the present impracticable to make it an 

 invariable part of a college education, by 

 imperatively increasing the length of the 

 college course, or by raising the standard 

 of admission to colleges, the device of a 

 post-graduate course has been very general- 

 ly adopted ; and it will not be long before 

 experience will demonstrate that those men 

 who have received the most thorough pre- 

 paratory training are able to overtake and 

 to outstrip in the subsequent race of life 



