FRAGMENTS OF SCIENCE. 



431 



of the most complex and arduous astronom- 

 ical questions. He was a member of the 

 commission to observe the great solar eclipse 

 of 1868 and the transits of Venus of 1874 

 and 1882. His most considerable book was 

 the Traile de Mecanique Celeste, which was 

 published in 1890, and has become an au- 

 thority on the subject. His other principal 

 books are the Lunar Tables ; a treatise on 

 the Movement of the Planets around the 

 Sun, according to Weber's Electrodynamic 

 Law ; a work on Shooting Stars ; Observa- 

 tions of the Sun Spots at Toulouse in 1874 

 and 18*75 ; and a collection of Exercises on 

 the Infinitesimal Calculus. 



Bacteriologists, says Sir Joseph Lister, 

 are now universally agreed that, although 

 various other conditions are necessary to the 

 production of an attack of cholera than the 

 mere presence of Koch's comma bacillus or 

 vibrio, yet it is the essential substance of the 

 disease ; and it is by the aid of the diagno- 

 sis which its presence in any case of true 

 cholera enables the bacteriologist to make 

 that threatened invasions of this awful dis- 

 ease have of late years been so successfully 

 repelled from Enghsh shores. " If bacteri- 

 ology had done nothing more for us than 

 this, it might well have earned our grati- 

 tude." 



NOTES. 



The observation made by Mr. Alfred 

 Springer five years ago that the acoustical 

 properties of aluminum are approximate to 

 those of wood, has been verified by continued 

 experiments with sound-boards of that metal, 

 and the author exhibited in the American 

 Association several aluminum violins, to- 

 gether with a device, called a bass bar, by 

 means of which the quality of the tone pro- 

 duced by the instrument can be controlled. 



According to President T. Kirk, of the 

 Wellington (New Zealand) Philosophical So- 

 ciety, the chief agents, next to man, in the 

 destruction of native species of plants in the 

 colony, whereby the way is cleared for in- 

 troduced species, are sheep, rabbits, and the 

 black rat. These animals have almost laid 

 several districts bare, leaving only the sturdi- 

 est and most persistent growers. Introduced 

 plants silenes, whiteweed, docks and sorrels, 

 chess, and velvet grass have nearly driven 

 out the original littoral vegetation in some 

 places. Even more destructive are the rav- 

 ages caused by the parasites which these 

 strangers bring with them. While the first 

 catalogue of naturalized plants in New Zea- I 



land, published in 1855, comprised forty-four 

 species, the present number is put by Mr. 

 Kirk at three hundred and four, and by 

 others at three hundred and eighty-two. 



The ruins of Tepoztlan are regarded by 

 Mr. H. Saville as especially important be- 

 cause they are the only American ruins to 

 which a definite date can be attached. The 

 sign of Ahuizotl, the immediate predecessor 

 of Montezuma, is engraved on one of two 

 slabs in the walls, and on the other the date, 

 ten Tochtli, which corresponds to 1502. 



Dr. H. C. Hovey called attention in the 

 Amei-ican Association to certain old monu- 

 ments in colonial graveyards, particularly at 

 Byfield and Newbury, Mass., and also to 

 some milestones and stones in the founda- 

 tions of old houses, which were carved in a 

 style very unlike that of Puritan monuments. 

 The symbols on them are pagan rather than 

 Christian, and include disks, vfhovXs, fleur-de- 

 lis, phallic signs, and a design representing 

 the sun-gods' bride with a sunburst over it. 

 It may be suggested as a solution of the 

 enigma they present that the maker of them 

 had seen figures of the kind somewhere, or 

 pictures of them, and copied them in the de- 

 sire to offer something new and striking. 



In one of his papers on the history of 

 Niagara Falls, read in the American Asso- 

 ciation, Mr. G. K. Gilbert presented evidence 

 of a former outlet of Lake Algonkin drain- 

 ing the upper lakes, heading at Kirkfield, 

 Ontario, and following the Trent River to 

 Lake Ontario, which belonged to an earlier 

 date than the outlet through Lake Nipissing 

 and the Ottawa River. There appear, there- 

 fore, to have been two periods after the 

 origin of the Niagara River in which it was 

 an outlet for the Erie basin only, and did 

 not carry the waters of the upper lakes. 



The making of the Mammoth Cave is 

 attributed by the Rev. H. C. Hovey, D. D., 

 in a paper read before the American Asso- 

 ciation, wholly to the solvent action of water 

 upon the limestone. No earthquake dis- 

 turbance or pot-hole action in the deep 

 parts of the cave can be considered as hav- 

 ing had any important effect upon the exca- 

 vation. 



" What is the bark ? " is asked in a pa- 

 per read before the American Association by 

 C. R. Barnes, who calls attention to the vary- 

 ing use made of the term bark by different 

 botanists. The Germans use Borke and 

 Rinde to denote respectively the external 

 tissue of the root or stem which dries up, 

 and the entire mass of tissue outside the 

 cambium. In this they are followed by the 

 English ; and the American usage, except as 

 modified by foreign influence, assigns the 

 name bark to the entire mass of tissue out- 

 side the cambium. In this use we are fol- 

 lowed by the French. The author advocated 



