424 



THE POPULAR SCIENCE MONTHLY. 



idea. Abercrombie tells a story of a lady 

 who in extreme infancy was brought to her 

 dying mother in a strange room to be taken 

 leave of. Long afterward, having grown 

 up with no recollection of her mother, she 

 went into the room again, for the first time 

 afterward, without the fact with which it 

 was associated having been mentioned, when 

 the whole scene of the leave-taking came 

 back to her with force. Had not the con- 

 nection of events been clearly traced, this 

 instance would have been classed with the 

 curious impressions we are considering. 



Velocity of Pnlse-Waves. — Continental 

 physiologists have determined that the ve- 

 locity of the pulse-wave is about twenty 

 feet a second, and that the rapidity of its 

 progress is essentially dependent upon the 

 rigidity of the tubes through which it trav- 

 els. Dr. A. T. Keyt, of Cincinnati, has sup- 

 plemented their observations by experiments 

 to determine the effect of other conditions 

 in modifying the speed. He first set him- 

 self to determine the precise influence of 

 tubes of different degrees of stiffness or 

 elasticity on the velocity of the liquid waves 

 sent along their interior, and selected for 

 this purpose, first a glass tube, then India- 

 rubber tubes of varying strength and firm- 

 ness of pull, then tubes made of chicken- 

 gut, and finally the aorta of a calf. The 

 experiments demonstrated that the velocity 

 of liquid waves in clastic tubes is propor- 

 tional directly to the stiffness and inversely 

 to the elasticity of the tube traversed ; and 

 they indicate the important modifying influ- 

 ence which the state of the arterial walls as 

 to stiffness or elasticity must exert upon 

 the rate of pulse-propagation in living ar- 

 teries. In the series of tubes which he 

 used, the velocity fell gradually from 216 

 feet per second in a tube of glass to 12-'75 

 feet in a calf's aorta. In further experi- 

 ments it was found that the rate of pulse- 

 propagation is not affected directly by the 

 manner of the heart's action, whether it 

 beats quickly, launching a sharp wave, or 

 slowly, sending a sloping wave ; that, other 

 things being equal, the pulse-wave travels 

 more slowly along large, and faster along 

 small, arteries ; that mere distance from 

 the heart neither accelerates nor retards 

 the velocity of the beginnings of pulse- 



waves, while the modifying influence of 

 different pressures is small at most; that 

 liquid waves travel along elastic tubes at 

 the same speed, whether the liquid be at 

 rest or freely flowing; and that the con- 

 sistence of the fluid makes no difference in 

 the velocity of the wave. 



The Earthquake of September 19th.— 



A light earthquake-shock was felt in West 

 Virginia, Ohio, Indiana, and Slichigan, on 

 the 19th of September, between half -past 

 two and three o'clock in the afternoon. The 

 estimates of its duration vary from five to 

 twenty seconds. No damage was done be- 

 yond the displacement of lij^'ht articles, the 

 throwing down of a chandelier in the insane 

 asylum, and the jarring down of a freshly 

 built arch, at Columbus, Ohio. In some 

 places, schools, a Methodist conference, a 

 woman's missionary society, etc., were tem- 

 porarily dispersed by the panic. An ob- 

 server at Indianapolis noticed that the 

 tremor ran from east to west, and anoth- 

 er counted seventeen distinct vibrations. 

 At Lawrenceburg, Indiana, and at Toledo, 

 Ohio, the indications were that the wave 

 passed from southwest to northeast; at 

 South Bend, Indiana, the motion appeared 

 to be from north to south. At Wheeling, 

 West Virginia, it was from northeast to 

 southwest. A Signal-Service officer at Cov- 

 ington, Kentucky, who was reading the ther- 

 mometer at the time, observed no agitation 

 of the mercury. Boat-captains at Detroit 

 say there was a noticeable rise in the river 

 at the time of the shock. The earthquake 

 was also felt at London, Ontario. 



Hibernation of Snakes. — Mr. Arthur 

 Stradling is investigating the hibernation of 

 serpents, with particular attention to the 

 greater sensitiveness to cold which they 

 show in the spring than in the fall. He 

 had under observation during last winter 

 twenty-six snakes of different species. Some 

 of them fed last in the latter days of Sep- 

 tember ; and then they retired to the hiber- 

 nating place provided for them at intervals 

 one by one, the first one when the tempera- 

 ture had fallen to 41°, the last one on the 

 2d of December. Occasionally, some of 

 them came out, under the temptation of 

 warmth or light, when " it was most ex- 



