xlviii GENERAL SUMMAKY OF SCIENTIFIC AND 



thinks that possibly in this way roots may insinuate themselves into 

 rocks far anterior in age, and thus be regarded as much older than 

 they really are. 



Lescoeur has studied the influence of chemical character upon the 

 gyratory motions which are observed whenever certain substances, 

 such as camphor, for example, are placed on the surface of pure 

 water. He has obtained the result wdtli the acids belonging to the 

 fatty series and with many of their acid salts, though only in a 

 slight degree with normal salts. A fragment of glacial acetic acid, 

 for example, moves very actively on w^ater and dilute acetic acid, 

 but not on the concentrated acid or on mercury. So also of propi- 

 onic, butyric, and valeric acids. 



May has published a memoir on hydrodiffusion, or the diffusion 

 of a heavier liquid into water, in which he gives experimental and 

 mathematical evidence to sustain the hypothesis of Fick or a mod- 

 ification of it that the passage of a dissolved substance from one 

 solvent to a second proceeds according to the theorem which Fou- 

 rier established for the passage of heat along a conductor. 



Guthrie has investigated the conditions of production of station- 

 ary liquid weaves in both circular and rectangular troughs, intend- 

 ing therefrom to deduce the velocity of wave progression from the 

 frequency of the recurrence of a given phase in the same place. 

 With circular troughs he noticed that with binodal motion ^, e., 

 motion produced by oscillations at the centre the number of vibra- 

 tions is independent of the amplitude and of the temperature; that 

 the normal rate of pulsation is not reached unless there is a depth 

 of at least six inches; that the chemical nature of the liquid is with- 

 out effect on the rapidity of oscillation; that the rajDidity of progres- 

 sion of such waves varies directly as the square root of the wave 

 length ; and that the nodal line of such circular waves is one sixth 

 of the diameter from the circumference. Hence it follows that a 

 wave a meter long would travel 83.07 meters a minute, or a little 

 more than three miles an hour. 



Marey has published a valuable memoir on the movements of 

 liquid waves in elastic tubes, in wdiich are given the results of experi- 

 ments made to elucidate the circulation of the blood, particularly 

 w^ith reference to the character of the pulse as determined with the 

 author's well-known sphygmograph. By means of a very ingenious 

 little apparatus called an explorator, several of wiiich are placed 

 along the length of the tube through which the wave moves, com- 

 pressed air is made to move a style at the instant the w^ave passes. 

 This style records the movement, both in time and in form, upon a 

 blackened cylinder, whose, surface moves twenty-eight centimeters 

 per second. The author's conclusions from these experiments have 

 a high physiological imj)ortance. 



The same author has contrived an ingenious dial log for vessels, 



