TRANSACTIONS OF THE SECTIONS. 
11 
o' view, it is well worthy of being recorded. Two Calotype examples of seleno- 
;r»|ihy form additional illustrations of this paper. The small moon, fastened on a 
inner of the larger picture, was taken by Mr. Henry Pollock with a double com¬ 
bination of short focus, and in less than a second. The bright point of Tycho, 
■ \:«h on so small u scale, is well marked at the top of this minute Calotype, and 
i h-jv-s to which 1 have already referred, give their more sombre reflection at the 
Mtiim. This is chiefly of interest as showing the decided energy of a power which 
s furaier years was supposed to be absent. 
Tin- more important drawing is a large positive picUne of the full moon, nearly 
*‘oc inches in diameter, and therefore on a scale of about ’250 miles to the inch, of 
stick the negative was taken, on the 6th of September, in the focus of the * Craig 
•-•'.''ujie,* at Wandsworth, whose diameter is 24 inches and focal length 77 feet,— 
n.'i when I state that it is the first attempt, it will be received, notwithstanding 
cm *'« imperfections of manipulation, which are not conceulcd by artificial tinting, 
i Hep iu the right direction. All the mure important features of the moon's sur- 
oc" will be discovered by those who are familiar with their telescopic appearance, 
i tin- portion of the eastern hemisphere admits of interesting comparison with the 
•'. i daguerreotype copy already described. We find in both, and with almost equal 
-mctnc>b, the Mare Crisium with the bright surrounding country which separates 
' ,r -m the Mure Free und it at is and Mare Trnnnuillitatis to the south and west,—the 
' r it' 1 \lPllo|rtlt>- mUl, iL. .. I 1 I .« a I _miln.l fllO 
r,i|’-v “ Je ‘ we have t,ie bright Aristarchus, Kepler, C opernicus, and lycno, 
1 a'- streams of molten lava extending over the southern hemisphere; but owing 
p ' °f ^11 moon, the craters and mountains are not relieved by shadows. 
,,'I'?! °/-r x *! uauro of the collodion negative was thirty-five seconds; but it is 
_ J.vchn and the brighter portions are overworked. In the absence also 
irJ <|U M 0ri r’ mounliu ?' perfect steadiness could not in the first instance be 
' , r ‘ ” rav »tt applied a micrometer screw to the eye end t»f the telescope, 
•- niuHc,, Wlt 1 a w ‘ nc « handle, and when the moon was on the meridian this 
V : ““Amount to an equatorial motion for the space of thirty-five seconds. 
•' (1 . c , across an aperture iu u slip of wood was placed close behind a 
, ui) ■ “ e " ,n the focus of the telescope, and Mr. Gravatt found that by humming 
r 'hmialivT ur , n ^ le handle of the micrometer so steadily as to keep Aristarchus 
"'uated th* o! eC e r Ml ' - Prout * w ho prepared the collodion surface, unfortunately 
tiiis,. 0 f u . .. C ?. n “ s to ° loudly for ' the man at the wheel,’ and hence arose a little 
l,f ''M'ojurp a 1 ' Ue 1 ss ' which was afterwards prevented hy mv attending to the time 
' b, -‘ imiil ? ea i ° f Mr ‘ Prout - Collodion pictures of the moon, as well defined 
“irrely anvil,i!’ * g , rou,lJ S lass > and taken through nil her phases, would leave 
' W-Rla« s iu-if to , i0 desired in consequence of the magnifying power of the 
^umei. and Mature experiments will be directed by Mr. Craig into this 
■' ‘ n a mum „• 1 'd 1 °f September, we renewed our attempt when the moon 
! ' ttea »g P°»ltian; hut an undetected source of error, and the 
' ^ I ,r ocurin» a ■ thc ‘ f °8 when the moon was on the meridian, prevented us 
" (11 Stained h, CCe8Sful Qp Sat‘ve. Moreover, the true photogenic focus has not 
i n. n . J D i Weans o1 f kiiIhIvg.. 1 .tato Iuiwpvi'I'. that the 
' >i ‘' H 1,1 ita conff 8C ,° pC * thnngli confcssedlv admitting of improvement in figure, 
i’Priced at a , V Ver lhp f uint«it points of light. That so large an object- 
uu! 1,0 »o much disadvantage bv hand, and unt machine polished. 
| Vatt . to take il " 1 lu ^th, the morning following, l endeavoured, wirn 
[- t . .. ‘“Weeded hv an * SUn on l * le meridian, and on the same scale as the moon ; 
v Wottlcd chara » n8lantar,CQU # operatiun in exhibiting, in the negative, the 
ac ei °f the surface which is usually brought out by high mag- 
