The Arkansaw traveler., 1884-09-20

Cs@pisf fsv Zzs Arksss<s Trsvxis,.
 scIENTIFIc MISCELLANY
 The making of large ienses is a matter Of many difficulties, e msy be inferred from the fact that there have been nine teen failures to cast the thirty-six inch glass for the great Lick telescope to be mounted in California.
 An investigation of the saltpesre beds neax Cochahamba, Bolivia, leads Mons. Sacc to conclude that this vast deposit, large enough to supply the whole world with its nitrate of potash, is the result of the decomposition of an immense colaec- tion of fossil animal remains.
 Botanists have evidence that trees may attain very long lives. The age of an elm has been estimated at 33s years; that of some palms, at from Goo to 700 yeas; of a plane-tree, at 7eo Of cedar, at Boo of an oak, at I,5oo of yew, at 7,6So; of taxodium, at 1000; and of a baobab-tree, at 5000 years-
 Above London the water of the Thames is found to hold in solution two cubic inches of oxygen gas per gallon, while near the point where the city's sewage is discharged it contains only about half cubic inch. A htsle lower down, however, the rivex recovezs nearly its original proportion of oxygen.
 In recent address, MT. Spence Bate, F. R. S, stated some interesting facts concerning the deterioration of teeth noticed as ve ascend the scale of animal life, the inference being that seeth arc gradually evolved into brain matter. and that with mans further increase in in- tellect may come the entire disappearance of his natural teeth.
 An increase of the proportion of oxygen in air nay be effected, according to a German authority, by aspirating current of air through several layers of tafieta which have been plunged in al- cohol or carbon disulphide, and then coated with thin layer of caoutchouc. Passage of air through four such layers is said to reduce its proportion of nitro gen to five per cent.
 Tobacco and the Heart.-The danger of tobacco-smol<ing is manifested, Dr. Troitski thinks, in its effect upon the ac- ton of the heart. During a series of observations he found that in every case, varying according to the condition of the individual, smoking produced an accel- ezation of the pulse-rase and a slight elevation of temperature. Representing the temperature of those who do not smoke by I.ooo, that of moderate smok- CTS would be I,oo8, and while the heart in the former case was making 1000 pulsations, in the latter i: would tsat I,ISo times.
 When We Grow.-Some interesting re- suits have been yielded by the invessi- gations concerning human growth which have been made by committee o4 the british Association for the Advancement of Science. It is shown that growth is most rapid during the 6rst five years of life, when both sexes grow alike, the boys being ittle taller and heavier than the girls. From Eve to ten the boys grow a little faster than the girls but from ten to fifteen the girls grow the faseez. and betveen the ages of eleven and . half and fourteen and half are actually taller than the boyA while from twelve and half to stteen and . half they arc heavier. The boys thea take the lead, growing at first rapidly but afervard slower, and complete their growth at about the twenty third year. It is generally supposed that @grown ups people de not increase in height, but these ressarches appear to show that men gain slowly in stafure un- til their 6fiesh year, and they make a more rapid increase in weight cp to the age of sixty. Statistics are too ineom- plrte to determine the growth of women after the age of twensy-shree.
 Sun SeormA-How can ve, who are bewildered and appalled, by the fury of our planets cyclones and volcanic ezup- tioas, fosm a couceptiea of the henibie energy of natural operations on the sunG Prof Newcomb suggesss that if we call the solar chromosphere aA ocean of frs. we mua remember that t is a ocaau hoeser than the 6erceH furnace, snd as deep as the Atlantic is bEoad5 five can its movemsnts hurricanes, ve mus re- member that our huEEicanss haow only aboat . AusdEsd miles n hour, while tAose ofthe chromospheze Slo~ as far in