98 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
Of the various mechanical devices used for trisection the linkage 
of Thomas of Ceva was given, others being referredeto only. 
Of false trisections, the number was stated to be very large and of 
unequal value, some giving close approximations and others failing 
ignominiously. Finally, in the bibliography, now containing some 
fifty references, and believed to be only the beginning of a reason- 
ably full list, it was proposed to make an authors’ catalogue of en- 
tries, and to follow each reference with a very brief characterization 
of the contents of the article. 
The foregoing scheme had beet laid out but latterly had made no 
progress, and the opinion of the section was sought as to the desira- 
bility or advisability of carrying the work on. 
Mr. Curtis made the following remarks: 
Six or eight years ago I began a similar collection of trisection 
methods, in looking over which I find a number of solutions addi- 
tional to those presented by Mr. Baker. 
The following six belong to the class in which an angle is trisected 
by means of curves : 
(1) y+ ay — azy + bx? =0; 
the ophiuride of Dietrich Uhlhorn (1764-1837). 
(2a? — yp)? 
. 
(2) Ae 4a? — y 4 
the polyode of Dr. Wm. Hillhouse,* Prof. J. W. Nicholson,} J. Bruen 
Miller.t 
(3) Ao? + 12y?=(VY1—a? + 9) — 8y V1 — +4. 
Dr. Wm. Hillhouse. 
(4) [Curve drawn, but equation not given. ] Ibid. 
*The Analyst; edited and published by J. E. Hendricks. 8°. Des 
Moines, Iowa. 1882, November, vol. 9, no. 6, pp. 181-:84. See also same, 
1876, September, vol. 3, no. 5, p. 151. 
ft Same. 1888, March, vol. 10, no. 2, pp. 41-48. See also The Multisector 
and Polyode. By Prof. J. W. Nicholson, M. A., Professor of Mathematics. 
Louisiana State University. 8°. New Orleans; published at the Times- 
Democrat. 14 pp. 
${ Van Nostrand’s Engineering Magazine. 8°. New York, D. Van Nos- 
trand, 1880, March, vol. 22, no. 135, pp. 206-209. 
