ae es Pots I must confirm 
T. W. Backhouse—Physiological Optics. 805 
Pickett’s Hill, in Fabius, Onondaga county, shows the Tully 
about 1680 feet above the sea. A second station, over a mile 
east of DeRuyter village, Madison county, is distant from the 
first six and a half miles in 2 southeasterly direction and is 
about 260 feet lower, a dip of 40 feet per mile. The third 
station, near the village of Gaslen % in Cortland county, is also 
six and a half miles from the first, a little west of south, and is 
about 365 feet lower, being a dip of 56 feet per mile. Hence it 
Sani seem that the he of the strata increases cae pontcens 
ron were ota oe scale from an accurate map lo Ca 
Lake made by the Engineer Department of Cornell — : 
and are doubtless correct. The remaining distances 
taken by scale from Asher and Adams’ Atlas of New York, , 
verified i comparison with a large map of New York and 
Gieiticn: 
ee tas donee tases io ¥., Aug. 3. 
—=—=. 
T eoas XXXY. — Physio Dptiesj by THoMas Warn | : 
— are some points in Mr. W. Titoee Stores oe 
published in this Journal, to which I take exception, though — 
2 € papers go to disprove Brewster's theory that the mode 
: et judg gment of distance in binocular Phong it ae Lh optic 
_ -“SBte, interpreted by means of triangulation. venss — 
eS Objections to this dics seem to me to ea untenable. _ I gather 
that he LeConte’s theory as insufficient, though he 
- bec ly accepts it I shall proceed to criticize some of Stevens's: 
= "Vol. xxiii, p. 291.—He discards the theory of vissal Tines 
and of corresponding retinal points, and substitutes that of asso- ; 
- cia uscular action. But if this be the true one, must : 
oe Pets first a. derived from observation of the intersection | 
i a tadertand the theory of corresponding Points to ee th i 
Drain causes each point. etina to appear to cormncide — 
@ point on the other, se Coil 
