178 



SCIENCE. 



[N. S. Vol. XXI. No. 527. 



trucks, fitted -with twin rings of double ball 

 bearings of the Chapman type. The treads 

 of the wheels are coned to the exact angle 

 which will make their apexes all coincide 

 with the point at the center of the plane of 

 the circular trucks. Ease of revolution of 

 the dome depends very largely upon the 

 accuracy with which this adjustment is 

 made and maintained. The necessary con- 

 dition has been secured by attaching a 

 small galvanometer mirror to the axis of 

 each truck, and adjusting it normally. A 

 theodolite mounted at the center of the 

 dome then gave the reflections of its ob- 

 jective exactly centered on the cross wires, 

 when the axis of the truck was brought to 

 the proper direction. 



An Exkihition of a New Form of Frame 

 for Straight Line Mathematical Models: 

 Professor C. A. Waldo, Purdue Univer- 

 sity, Lafayette, Ind. 



A new form of thread model for ruled 

 surfaces was exhibited by Professor Waldo, 

 the frame for the model being conformed 

 to the surface of a sphere, thus permitting 

 location of the points of attachment of the 

 threads with much greater ease than in the 

 ordinary forms in which the limiting sur- 

 face is discontinuous. The method of con- 

 struction was also explained. 



The Application of Mayer's Formula to 

 the Determination of tlic Errors of the 

 Equatorial: Professor L. G. Weld, State 

 University of Iowa, Iowa City, la. 

 Let the polar axis of the equatorial be 

 rigidly clamped with the telescope first to 

 the east and then to the west of the pier 

 and the transits of three stars observed in 

 each of these positions of the instrument. 

 The clock correction being assumed known, 

 the errors of azimuth, level (of declination 

 axis) and collimation (in right ascension) 

 may be obtained for each position by the 

 use of Mayer's formula. From the two 



sets of errors thus made known the mean 

 azimuth error of the polar axis and the 

 angle between this axis and the declination 

 axis may be determined. The method is 

 independent of the accuracy of the hour 

 circle and may be used in correcting the 

 setting of this circle upon the polar axis. 

 When the hour circle is delicately gradu- 

 ated the data may also be used to determine 

 the flexure of the declination axis. 



Laenas Gipford Weld, 

 Secretary. 



ALBATROSS EXPEDITION TO THE EASTERN 

 PACIFIC* 



The Albatross, under command of Lieut.- 

 Commander L. M. Garrett, left San Fran- 

 cisco on the sixth of October and arrived 

 at Panama on the twenty-second. I am 

 fortunate in having as assistant for this 

 trip Professor C. A. Kofoid, who has had 

 great experience in studying the protozoa 

 both in fresh water and at sea ; he has been 

 given charge of the collection of radio- 

 larians and diatoms and of other minute 

 pelagic organisms; and he will prepare a 

 report on the results of that branch of the 

 expedition. On the way along the coast 

 Professor Kofoid took advantage of the op- 

 portunity for making surface hauls with 

 the tow nets as well as vertical hauls, gen- 

 erally to a depth of 300 fathoms. A large 

 amount of pelagic material was thus col- 

 lected, not at a great distance from the 

 coast, however. Off Mariato Point the 

 Albatross made two hauls in the vicinity 

 of the stations where in 1891 she found 

 'modern green sand,' in about 500 and 700 

 fathoms. It was interesting to find the 

 green sand again, as the specimens collected 

 in 1891 were lost in transit to Washington. 



Immediately on reaching Panama the 

 vessel was coaled and provisioned. On my 



* Extract from a lotter of Mr. Alexander 

 Agassiz to Hon. George M. Bowers, U. S. Fish 

 Commissioner, dated Lima, November 28, 1904. 



