THE POPULAR SCIENCE MONTHLY. 



and earth vibrations. A muddy stream is- 

 sues from them, of varying fluidity, rolling 

 along lumps of peat. Then the mud hard- 

 ens and the bog sinks back, forming a fun- 

 nel-shaped pool. The bogs studied by the 

 author have been mostly on high ground, 

 not in valleys. He believes that the erup- 

 tions are not caused either by excessive ab- 

 sorption of moisture or by gas explosions — 

 the theories most readily suggested — but by 

 land-slips, collapses, etc., of ground under 

 the bog, which permit water or liquid mud 

 to enter. This breaks up the bog mechan- 

 ically, mixes with it and fluidifies it, and 

 produces the outburst at the surface. The 

 limestone formations in Ireland, with their 

 large caverns and masses of water, are natu- 

 rally subject to these collapses, which, with 

 the vibrations they induce, are more fre- 

 quent in wet years. The heavy rains preced- 

 ing the bog eruptions are thus to be regard- 

 ed as only an indirect cause of them. Herr 

 Klinge supposes that similar eruptions oc- 

 curred in past geological periods, the Car- 

 boniferous, for example, in some cases where 

 fossil tree-stems are found in upright po- 

 sition. 



NOTES. 



In a paper in the British Association, on 

 the Periodical Velocity of Bubbles in Vertical 

 Tubes of Liquid, Mr. F. T. Tronton said that 

 as a bubble ascended in a tube its changes 

 of shape caused corresponding changes in 

 its velocity, and consequently any given bub- 

 ble if watched would be seen to have alter- 

 nating maxima and minima of velocity. 

 Further, the rush of water backward from 

 the front to the rear of the bubble in the 

 narrow channel between the latter and the 

 wall of the tube was greatest when the bub- 

 ble had its maximum elongation. By mak- 

 ing the liquid more viscous we could arrive 

 at a point where it became uncertain whether 

 the bubble would ascend the tube in the long 

 or flat condition, but having started either 

 way it would continue in its original shape. 

 At this particular viscosity the velocity of 

 ascent was a maximum. Lord Kelvin, as Sir 

 William Thomson is now called, suggested 

 an application of this result to certain en- 

 gineering problems, and particularly spoke 

 of the possibility of nullifying the retarding 

 effects of the viscosity of water upon the 

 sailing of ships. 



The Mexican jumping seed, or "devil's 

 bean," is a euphorbiaceous plant of such 

 poisonous properties that it is used by the 



Indians to envenom their arrow-points. It 

 not having been scientifically identified to 

 satisfaction, Dr. C. V. Riley has made a spe- 

 cial study of it. The saltatory property is 

 not intrinsic with it, but is imparted to it by 

 an insect {Carpocapra saltitans), which se- 

 cures lodgment within the bean and does the 

 work. Dr. Riley believes that the insect is 

 developed in the capsules of several species 

 of the genus Sebastiana. 



It is said that a larger cave than the Mam- 

 moth Cave, situated in the Ozark Mountains, 

 near Galena, Mo., has been explored for a dis- 

 tance of more than thirty miles. In it have 

 been found bones of recent and prehistoric 

 animals, including the hyena and cave bear, 

 and flint arrow-heads, but no bones of man. 

 A few animals of the usual forms found in 

 caves are still living there, including a white 

 newt. 



Phosphatic marls, according to the re- 

 port of Mr. E. A. Smith, State Geologist, 

 have been found in Alabama in the Creta- 

 ceous and Tertiary formations. When they 

 were first brought to notice a spirit of specu- 

 lation was aroused, which subsided when it 

 was found that they did not include in com- 

 mercial quantity high-grade phosphates suit- 

 able for exportation. Dr. Smith, however, 

 regards this as to the advantage of the State, 

 because it will cause the fertilizing mate- 

 rial to be used at home, to the enlargement 

 of its crops, as has occurred in New Jersey 

 with its low-grade phosphates, instead of be- 

 ing exported as are the high-grade phos- 

 phates of South Carolina, which has, agricult- 

 urally, derived no more benefit than other 

 States from its precious stores. 



OBITUARY NOTES. 



The eminent French philosopher and 

 man of letters, Joseph Ernest Renan, died 

 October 2d. He was the son of a sailor, 

 and was born in Brittany, February 21, 1823. 

 He was educated for the priesthood, and 

 proved to be a remarkable student, but the 

 result of his studies was to make him a 

 theist instead of a Christian priest. His 

 most widely known work is his Life of Jesus, 

 which is one of a series of books on the 

 origins of Christianity. He was also author 

 of a History of the People of Israel, in five 

 volumes, and wrote much on Oriental phi- 

 lology and archaeology, in which subjects he 

 was an adept. For many years he was Pro- 

 fessor of Hebrew, Syriac, and Chaldaic in 

 the College de France. 



After some years of ill health, George 

 Croom Robertson died September 20th, at the 

 age of fifty-one. On account of illness he 

 had recently resigned his professorship of 

 Philosophy and Logic in University College, 

 London, and gave up the editorial charge of 

 Mind last year. 



