446 



SCIENCE. 



[N. S. Vol. IV. No. 91. 



tively later, and tlie bottoms of the spires to 

 an earlier stage than the corresponding 

 mean time of spinning on a plane tablet. 



Now if the pencil is hard, so that its cir- 

 cular edge remains nearly constant in radius, 

 the envelope of the cycloido-spirals will con- 

 sist of two straight lines converging at the 

 point where the top would cease to rotate if 

 the other conditions of motion remained 

 similar. In other words, supposing the 

 period of precession to be nearly constant, 

 the angular velocity of the top would vanish 

 at the point of intersection in question. 

 The cause of the gradual cessation of mo- 

 tion here, as in case of the horizontal tablet, 

 is friction ; but in case of the oblique tablet, 

 if the period of percession remains nearly 

 constant, the crests of the spires correspond 

 to smaller angular velocities, and will there- 

 fore have smaller radii of curvature than 

 the troughs of the spires where angular 

 velocity passes through a maximum. In 

 other words, the loops will be less obtuse 

 at the top and more obtuse at the bottom 

 of the dip. Part of the energy of rota- 

 tion is periodically potentialized. To draw 

 such curves the top must necessarily move 

 across the dip. 



If the end of the pencil is convex, so that 

 the rolling on the pivot is relatively de- 

 creased as the top rises, the envelope of the 

 spires will no longer be straight, but con- 

 sist of two converging curved lines as 

 shown in the figure. 



In the preceding instances the direction 

 of the progressive motion of the top, i. e., 

 the trend of the '■ cornucopias, ' is nearly a 

 straight line at right angles to the dip. 

 Suppose, however, that for the plane tablet 

 a flat conical one be substituted, which may 

 be either raised or depressed in the center. 

 The dip is now everywhere radial. In 

 this case the progressive motion of the top 

 becomes orbital around the axis of the cone, 

 if the dip be suitably chosen. We have 

 then a very simple arrangement for simula- 



ting (except, of course, as to cause, and quan- 

 tity) the orbital and precessional motion of 

 the earth. Indeed, beautiful fluted curves 

 corresponding to nutational movement may 

 also easily be obtained by slightly destroy- 

 ing the balance of the top, though this in- 

 terferes somewhat with the smoothness of 

 motion. C. Barus. 



Beown Univkesity, 



Peovidence. 



MEETING. OF THE 31 AZ AM AS AT CRATER 

 LAKE, OREGON. 



The annual field meeting of the ' Maza- 

 mas,' a club of mountain climbers with 

 headquarters at Portland, Oregon, was held 

 at Crater Lake, in the Cascade Mountains, 

 during the latter part of August. This 

 meeting was one of the most important and 

 successful ever held and was a memorable 

 one in many ways. Through the cooperation 

 of local Crater Lake clubs, of Ashland, Med- 

 ford and Klamath Falls, about 500 persons 

 were present. There were also present 

 members of four of the scientific bureaus of 

 the government. The various parties ar- 

 rived from the 14th till the 19th, and the 

 camp began to break up about the 25th. 



The Mazamas pitched their tents on an 

 eminence overlooking the wonderful crater, 

 and meetings were held evenings around a 

 huge bonfire in front of the tents. On the 

 evening of August 21st the ancient volcano, 

 whose summit is occupied by Crater Lake, 

 was christened Mt. Mazama. An appro- 

 priate address was read by the President, 

 Mr. C. H. Sholes, of Portland. This was 

 followed by a dedicatory poem by the Vice- 

 President, Miss Fay Fuller, of Tacoma, 

 Washington. Then the energetic Secre- 

 tary, Eev. Earl M. Wilbur, of Portland, 

 acting as / toast'master,' introduced the fol- 

 lowing toasts : To Mt. Mazama, responded 

 to by Mr. J. S. Diller, of the U. S. Geologi- 

 cal Survey ; to the Poetry of Crater Lake, 

 by Capt. Oliver Applegate, of Klamath 



