( Extract from " The Journal of Nervous and Mental DiseasesMarch. 1890.) 
A TEST OF WILSON'S CYliTpJIE'PEH. 
By H. J. Mulford, M.D. ?. 
Extract from a Thesis, to which honorable mention was accorded, presented to the faculty of the 
medical department of the University of Buffalo, January. 1889. 
The cyrtometer was designed for the purpose of locating the.position of the fissure 
of Rolando on the living head. It is described as follows : 
" The instrument consists of three strips of flexible metal and a tape (Z>, Fig. i) 
for securing it in situ. The broadest transverse strip (Figs. I and 2) passes coronally 
around the forehead, corresponding with the glabella and the external angular process 
(C and e a p, Fig. 2); the narrower longitudinal strip (5, Figs. 1 and 2) passes back- 
wards from the glabella in the middle line to the occiput. This strip is marked with 
two scales of letters: capitals in its posterior fourth, and small letters about the 
middle of the strip (A, e, Fig. i). 
G.TIEMANN &C0. 
Fig. r.-4-t-The Cyrtometer. 
" Measured from the glabella backwards, the distance to any given small letter is 
55.-7 per cent, of the distance from the glabella to the corresponding capital letter; 
thus, when any capital letter falls directly over the inion, the corresponding small letter 
will coincide with the .top of the fissure. A third narrow reversible strip (C, Figs. 
I and 2) slides on the longitudinal slip, making an angle of 67°, opening forwards, and 
marked at 3J inches from its attached end (F, Fig. 1), thus giving the length and di- 
re&ftXi of the ,WT1AMJHOT2 : The following are the scales : 
CAPITALS. 
SMALL LETTERS. 
Inches from glabella. 
Inches front glabella. 
■ A • 
E (l2) . | . 
sMOgjIW itHMl 
C (12.5) . 
c (6.9) 
D (13) • • 
• , • • d (7.2) 
E (13.5) .(! 
nsoHjnIZ .( ,H vfl • e (7.5) 
A (14) . 
• t, . ..'J: 1 wod moil 
G (14-5) • 
.. xjieiaViflU ->Hj Io 
The cyrtometer used by me differed a little from the above. It was made of elas- 
tic metal ribbon, such as is used for clock-springs, without a tape, its own elasticity 
Fig. 2.-The Cyrtometer in position. 
being enough to keep it in position. For this idea I am indebted to Dr. Roswell Park, 
who was then, and is now, doing considerable surgery of the brain. 
* * * Of the various methods proposed for locating the fissure of Rolando, I 
think Mr. Hare's the best, for these reasons! 
First. The Cyrtometer is quickly applied and easily retains its place. There are 
no planes to determine, no lines to draw, and but two landmarks are necessary. 
Second. It is as correct as any method can be in the present fashion of heads. 
Its errors are small, and when they occur need not be feared. I would advise its use. 
GEORGE TIEMANN & CO. 
■ tallol ilntm rnJv"vnr; w sMHuetv Jiradnlg orfj moirTawaEsM 
Manufacturers of' Surgical Instruments, 
107 PARK ROW, NEW YORK. 
MANUFACTURED AND FOR SALE BY 
*1; .hi 1 , uuj rjf moil sansni oaaicfn 
Branch Store: STOHLMANN, PFARRE & CO., 107 East 28th Street, New York.