M. C. Lea on some new Manipulations, — 375 
the presumed changes which some of the surrounding localities 
. 
have suffered in regard to their original stratification. 
Syracuse, Feb., 1866. 
Apt. L.—On some new Manipulations ; by M. Cargy LEA. 
J. Grapvation or Burertes. 
(1.) Seleetion of Tube. 
toa certain extent, that of the calculations, in actual use. In 
the following manner a variation in the diameter of the tube un- 
der examination, amounting to ;s';5 or less can easily be de- 
tected, 
i. 2, 3. 
wre 
ss 
ae 
A piece of thin glazed letter paper is cut to the shape represent- 
ed in fig. 1, this is wound tightly round the tube, making the sue- 
cessive folds perfectly correspond at bottom, a card is held to the 
paper, and a thin line is drawn with a fine pointed pencil, pass- 
ing over three folds of the paper as represented in fig. 2. 
