416 
REPORT—1854. 
produce a tint by which the distinction between the lighter and darker shade* 
on the moon s surf-ice is more perceptible. To my eyes the greenness of the 
shade soon vanishes, and the eventual tint is a subdued white. [On re¬ 
moving the green glass and looking at the moon’s surface, the complemcntan 
pm colour is strongly developed.] All the necessary explanation are 
given on the card* upon which the drawings are made, and in the note 
attached to them. , 
“James Chalus. 
“Interim Report on the 1 Mare Crisium and its Shorn'.” 
By Professor C. Piazzi Smyth. 
" September, 1854. 
, T bre . e ^ ar £ e drawings of this lunar region are transmitted herewith, ex- 
ibiting it under the three different phases of incident light recommended 
by the Lunar Committee of the British Association. They are likewise re¬ 
duced to a mean state of libration, and are on a scale of 98 inches to the 
diameter of the body. 
Ten original sketches made at the telescope, and on which the above com¬ 
positions have been framed, are also sent, with notes and explanations, aswvf 
flS f eton ma P for identification of features and places. 
the magnifying power employed, which was the highest possessed, and 
un'ortunatdy too much for the indifferent quality of the object-glass, was 
?nnf fc 20 °’ But experience has shown that the power of not less than 
iuuu, as recommended by the Committee, with suitable size and qu^ 
o o nect-glass, would have been in the highest degree advantageous. 
/• , ,act, ce and experience brought to view so many decided and interesting 
eaturos of colour, that the monochrome proposed was exchanged for Hie 
2?T?. S( T b0X ot ‘ flours, ground up first with water, butaft*** 
nns i * ’ n < i tter m<K fo appearing preferable, as white had as often n 
put m on black, as black on white! * 
pff J' t “ ae . (l 80 c fo“ e a» the Mare Crisium Is to the limb of the moon, ^ 
ettects of l.brat.on were found so extensive in altering the perspective, •“ 
the consequent apparent form of mountains, as well as the shade ol 
p 0n . !!tHnt a £° °f the moon, that special measures had to be ta 
correct for it. 1 
‘So extensive a surface as that proposed to 
tho nr 1 har,,l y be doue |u»tice to by only one drawing tn e« a 
ttepmnmM ncident light,, for when one boundary k 
manner n ihado ™* of ' elevation and depression in the moot b « ^ 
often verw e .. 0f, P° 8lt f boundary is then beginning to show those p>J". 
tion y lverse phenomena which are brought out by a vertica 
ti „““ Skater number of the sketches had been ob | ai '' cd ’ h 
I h ' Beer Madler’a map was referred to. The result 
£nhi *i°Z Ccd , ng great accura <7 a ™‘ admirable completely ' 
hi n P iv fre t P h artl ? ula . rs ’ 1 expressed in a certain conventional style; bat * ^ 
scone £ a, ' d ,nccb anic<U features, as they are sc . eU / 0 b e rf# 
in ? ’ th tbey CX, “ t “ nature, and in the form they are required ^ 
Indulged i„. PUrP ° 9e ° f enab,ln g any geological speculates to be 
for‘the shadino*2?®? 11 / . irn P 0saib,e for any one map to give 
blackness at ti? P vh,Ch 18 latr oduced to express the depth ofaC , to tln*“ | - 
dication of 1 ! P v ’ -° r old lnooiJ > is a ‘ once and directly opposed <° ^ 
full moon CeS8,Ve wh ««W» of its internal walls, as revealed 
