ON MAPPING THE SURFACE OF THE MOON. 43 
The transition, to which allusion has been made, was seen on the evening 
of the 26th of June by three observers. 
The next favourable opportunity for seeing Zinné near the terminator 
occurred on the 24th of August 1868. The following is a record of observa- 
tions by Mr. Walker, of Teignmouth :— 
1868, August 2447" 45™, Linné: crater on the top of a gently rising 
ground (conical shape), wall to right (east) in stronger illumination; below 
to left appearance of depression. Definition good. Could not make out any 
thing inside the erater ; crater looked clean ; no appearance of white cloud or 
haze.” 
Subsequently Mr. Walker furnished the following explanation :— 
“The gently rising ground I spoke of was exterior to Linné, nothing of 
the interior or floor of which was visible, the illumination not being yet high 
enough. By a conical shape (not a well-chosen phrase) I meant that the 
ground rose in all directions around Linné, which thus presented the aspect of 
a shallow crater on the summit of a rising ground. The impression of shal- 
lowness was conveyed by the thinness of the illuminated circuit of the cra- 
ter, and I think also. by the shade of darkness of the interior of the crater. 
Of the cone I saw nothing.” 
Mr. Walker’s observation very fairly agrees with those made on June 26. 
The rising ground appears to be the surface between the ridges upon which 
the cone or crater is situated. Mr. Walker speaks of the thinness of the cir- 
euit [ Qy. rim] of the crater, from which he inferred that it was shallow ; he is 
decisive upon the absence of the white cloud or spot. 
Under the evening-illumination of the same luni-solar day, on Sept. 7, 
1868, 11.30 to 12.0 L.M.T., Maresfield, Sussex, Capt. Noble recorded the 
following observation :— 
“With powers of 154, 255, and 394, Linné, which is now tolerably near 
the terminator, suggests the idea of being a mammillariform object. Isome- 
times seem to glimpse a darker (though by no means black) spot near the 
middle ofit, giving it the aspect of a thick ring ; but as the shading is in the 
opposite side to the sun, and is moreover faint, it is just possible that it may 
be the result of the convexity of this wonderful object.” 
Two hours later, viz. Sept. 7, 1868, 14", Mr. Walker, of Teignmouth, re- 
corded as follows :— 
“ Endoxus on terminator. Linné. Hill on east side of the crater bright. 
Crater dark inside. Curved ridge, N.W. cut by the terminator. Two other 
ridges S., the east one sweeping up to Sulpicius Gallus, which was very 
marked, round, and has higher walls than Linné, which is rather the larger 
perhaps of the two, and oval-shaped. Fancied the hill or elevated portion of 
the crater E. had a crater on it.” 
Mr. Walker's observation is accompanied by a sketch, from which it ap- 
pears that the portion designated as the crater is the surface between the 
ridges, the rising ground of the morning illumination, and that the hill on 
the east is the cone on which Mr. Walker thought he saw a crater (the cra- 
ter-opening) ; this hill occupies the precise position of the cone in the observa- 
tions of June 26. 
The observations of Mr. Walker and Capt. Noble, on Sept. 7, bear the same 
relation to each other as the earlier observations on June 26 do to the ob- 
servation of Messrs. Joynson and Williams on the same evening. In one 
case we have the topographical features of the district near Linné replaced 
by the white spot ; in the other the white spot is first seen, but in a short 
time it has disappeared, and the features of the district have become visible. 
; E2 
