BIBLIOGRAPHY OF IIERSCHEL's WRITINGS, 00.5 



Herschel, W.: Synopsis or the ^YRITIXGS of— Continued. 



A. D. Vol. r. 



The oxtonded views I have taken in tins and in my fnnncr papers of 

 the various parts that enter into the constnictiou of the heavens 

 have prepared the way for a final investigation of the universal 

 arrangement of all these celestial bodies in space. The scale is still 

 wanting by which distances are to bo measured. 

 1814 104 282 XX. Of the hrcakhuj ui) of the Milky Way. 



Its whitish thigc has Ijcen proved by star-gaugos to arise from ac- 

 cumulated stars. It does not now consist of equally scattered stars. 



283 One hundred and fifty-seven instances have been given of clusters 



situated within the milky way. Sixty-eight more are in the bor- 

 ders. Now, since the stars of the milky way are permanently ex- 

 posed to the action of a power whereby they are irresistibly 

 drawn into groups, we may be certain that from mere clustering 

 stars they will be gradually compressed through successive stages 

 of accumulation till they come up to what may be called the ripen- 

 ing period of the globular form, and total insulation ; from which 

 it is evident that the milky way must bo finally broken up and 

 cease to be a stratum of scattered stars. 

 The state into which the incessant action of the clustering power has 

 brought it at present is a kind of chronometer that may be used to 

 measure the time of its past and future existence ; and although wo 

 do not know the rate of going of this mysterious chronometer, it is 



284 nevertheless certain that since the breaking up of the milky way 

 affords a proof that it cannot last forever, it equally bears witness 

 that its past duration cannot be admitted to be infinite. 



Thj8 paper is accompanied by Plate IX, p. 284, with 17 figures. 

 Flo- l = H.v,46. Fig. 7 = H.iv,42. Fig. 13 = H. viu,44. 

 " 2 = H.iii,67. 8=-H.iv,fi9. 14 = H.viii,4. 



3 = H. ii, 706, 9 = H. iv, 33. 15 = H. vi, 3G. 



4 = Hi,143. 10 = H.iii,r.97. 16 = H.vi,5. 



5 = H. iv, 4. 11 = n. ii, 101. 17 --- M. 72. 



6 = H.iv,35. 12 = H.ii,500. 



1815 105 293 A series of ohscrvations of the sateUUes of the Gconjian planet, including 

 IBlo lOo ^^:4, ,;,,,„,,,;,,„,,, o/«.dror^,7.s; ^^manintrocluctoryacco.n^t 



of the keseopic apparatus that has heen uml on this occasion ; and a 

 final exposition of some calculated particulars ded,acdfro^ the obscn^- 

 tions. By William Herschel, LL. D., F. R. S. Read June 8, 181o 

 293 A telescope suitable to examine these faint objects must possess the 

 double power of magnifying and penetrating into space. 



^^ l^t:';xs:r^^s i"";s:tet ,....>. .., not ,.,o. ..«e 



295 



296 

 206 



The'mlchinery of my 20-foot telescope is so ^«°^Pl^!« ^^^f^.;^,,^^^'^ 

 been able to take up tl- planet at an early hour m he e^ e.m^^^^^^^ 

 to follow it for 7, 8, or 9 hours successively. The 40-ioot teu scope 

 has not b en always used because time is required for preparations. 

 tI temperature i"s often too changeable ; its use requires 2 work- 

 Tuen beside the assistant at the clock and writing-desk. 



The 20-foc:^tn be pointed on the planet with everything adjusted 



It^h^^Z^l^tly been a rule with me not to observe with a larger 

 instrument when a smaller would answer. 



