210 



SCIENCE 



[N. S. Vol. X:^XIX. No. 997 



members " previous torsion, and precision is 

 impaired ; the iron " remembers " the preced- 

 ing cycle, and energy is wasted in concen- 

 trating its wandering attention. 



Not the least remarkable thing about falling 

 stones, and gravitational action in general, is 

 the lack of hysteresis, or memory. 



WiLLARD J. Fisher 

 New Hampshire College, 

 Ddrham, N. H. 



lag and lead with a braun tube 

 In arranging an experiment to show lag and 

 lead with a Braun tube I hit upon a method 

 that was very effective and may possibly be 

 of use to others. 



The tube, with its axis horizontal, was ex- 

 cited by an induction coil with a break of 

 variable speed. Two coils were used to pro- 

 duce the magnetic field, one with its axis 

 vertical, and the other with its axis horizon- 

 tal, and both with axes perpendicular to the 

 axis of the tube. The distance of the one 

 coil from the tube could be varied. If an 

 alternating current was sent through the coil 

 with horizontal axis it would produce a verti- 

 cal line on the fluorescent screen when the 

 tube was excited. If now the period of the 

 vibrator of the coil was changed until the 

 frequency of the alternating current was 

 nearly equal to a multiple of the frequency of 

 the coil the stroboscopic effect would make the 

 spot of light move slowly up and down on the 

 screen. With the current flowing through the 

 other coil the spot would move back and forth 

 on the screen. When the alternating current 

 from the same source is led into both coils 

 the spot moves up and down diagonally at an 

 angle of 45°. 



If now considerable inductance is intro- 

 duced into one circuit the spot will move 

 around in an ellipse in one direction, but if a 

 condenser takes the place of the inductance 

 the spot moves in an ellipse in the opposite 

 direction. Varying the inductance varies the 

 width of the ellipse so that the amount of 

 lag or lead is roughly indicated. If both 

 inductance and capacity are put into the same 

 circuit the width of the ellipse is reduced, 



showing the neutralizing effect of capacity on 

 inductance. John Fred. Mohler 



Dickinson College, 

 November 28, 1913 



A SECOND OCCDRRENCE OF ICHTHYOSAURIAN RE- 

 MAINS IN THE BENTON CRETACEOUS 



In 1905^ Dr. John C. Merrian announced 

 'the discovery of Ichthyosaur-like remains in 

 the Benton of Wyoming. That it was not an 

 accidental occurrence now appears to be indi- 

 cated by the finding of a second specimen in 

 these same beds. Eecently I have received for 

 examination a single badly worn vertebral cen- 

 trum, collected during the summer of 1913 by 

 Mr. C. J. Hares, of the U. S. Geological Sur- 

 vey in the Mowrey shales, some 12 miles west 

 of Casper, Wyoming. This vertebra is of the 

 typical biconcave ichthyosaurian type and in 

 its present condition is indistinguishable from 

 those of Baptanodon. The fragmentary nature 

 of the specimen precludes the possibility of de- 

 termining its true generic affinities, but as re- 

 cording a second occurrence of ichthyosaur- 

 like remains in the Benton, the specimen is 

 at the least of interest. 



Charles W. Gilmore 



U. S. National Museum 



A misnamed portrait of JOHN SHAW BILLINGS 



To THE Editor of Science: Dr. S. Weir 

 Mitchell's appreciative memoir of the late Dr. 

 Billings in your current issue is not accom- 

 panied by a picture and does not refer to one; 

 so the present note may be acceptable. On 

 p. 223 of Vol. VII. of the " Photographic His- 

 tory of the Civil War " the upper right por- 

 trait represents Dr. Billings during the war 

 as an assistant surgeon with the rank of first 

 lieutenant ; it is misnamed " Brevet Lieut. Col. 

 J. J. Woodward." This legend really belongs 

 to the lower left portrait, which in turn is 

 misnamed " Brevet Major 0. B. Greenleaf." 

 To which of the two other portraits this be- 

 longs I can not say. In this connection may 

 be noted another error in the work above 

 named. In Vol. X., on p. 263, the portrait 

 named " David E. Jones " is that of Samuel 



1 Science, N. S., Vol. XXII., No. 568, pp. 640- 

 641. 



