!30 On somen/ 1 he Strata in the Neighlour hood of London f 



of the tube drawn out. lu this example — = — r = 



— , which by the table is = 15-22 seconds. 



Then 99" -6 x 18 — 15"-22 = i:77"'5S = Sg^'Sy'^-SS = 

 the apparent diameter of the moon at that time» 



Example ■■2. — Suppose the distance between two stars was 

 observed to extend over more than 15 divisions of the micro- 

 meter, but not 16, the eye-tube being drawn out -jig^th of an 

 inch ; but on drawing out the eye-tube -ja^dth parts of an 

 inch, their distance extended over 16 divisions : What was 

 the apparent angle subtended by those stars ? 



In this example 7^5 — 75 = ^jj which are = 8l"-9. 



Then 99"6 X 16 — 8l"-9 =]51l"-7 = 23' ll"-?, which is 

 the apparent angular distance between the two objects. 



This micrometer is rejtresented in fig. 5, PI. HI. The 

 middle part of the scale is divided into 20 equal parts by 

 parallel lines drawn at the distance of -i^dth part of an inch 

 from each other, and the large divisions on the sides are 

 each = y^dth parts of an inch. These lines are drawn as 

 fine as possible to appear distinct. 



Angles may be taken in any direction by this micrometer, 

 as it is easily turned round upon its axis; and as it is fixed 

 against the eye-stop only by a ring of wire, in the same 

 manner that glasses are fixed in ordinary instruments, it 

 may be taken out and put in again with as little trouble as 

 any other glass in the telescope. 

 I am, sir, 



Your obedient servant, 



Lynn. August 14, IS 11. E. WaLKER. 



XXX. Olseri'ntions on some of the Strata in the Neigh- 

 bourhood of Londo?i, and on the Fossil Reynains contained 

 in Ihcni. By James Paukinson, Esq. Member of the 



Geological Societi/*. 



X HE Study of fossil organized remains has hitherto been 

 directed too exclusively to the consideration of the speci- 

 mens themselves ; nnd hence has been considered rather as 

 an appendix lo botany and zoology, than as (what it really 

 is) a very important branch of gonlogical inquiry. 



Fron> a compurison of fossil remains with those living or 

 extant beings to which they bear the closest analogy, great 



* From the Tran'£c;jpns of the Cro'ogical '?'>ciety, vol. i. 



resem- 



