373] 
ON A SPECIAL SEXTIC DEVELOPABLE. 
519 
The like property exists for curves in space—viz. taking account as above of the 
new singularity of the stationary lines, then we have 
| (m — 1) (m — 2) — h — /3, 
= ^ (r — 1) (r — 2)—y—n —% 
= | (r — 1) (r — 2) — x — m — S-, 
= 2 (n-l)(n -2)-g-a, 
which equations are in fact at once deducible from the above-mentioned system of 
six equations between the quantities m, r, n, <x, ¡3, g, h, x, y, and may if we please 
be taken for equations of the system. 
If from a given curve and torse we derive a second curve and torse, in such 
manner that to each point (or plane) of the first figure there corresponds a single plane 
(or point) of the second figure—then the corresponding expressions l)(m'— 2)—li'—¡3', 
&c., have the same value for the second as for the first figure. 
Cambridge, April 11, 1865.