BIBLIOGRAPHY OF HERSCHEL's WRITINGS. G05 



Herschel, W.: Synopsis of the Writings of— Continued. 



A.D. Yol. P. 



Tho extended views I Lave tal<eTi in tliis and in my fonner papers of 

 the various parts that enter into the construction of the heavena 

 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 hreakhuj iqy of the MiUcy Way. 



Its whitish tinge has been proved by star-gauges 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 wuthin 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 accunnilation till they come up to what maybe called the ripen- 

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

 it is evident that the milky way must be 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 we 

 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. 

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

 Fi-. 1 = H. V, 4(3. Fig. 7 = H. iv, 42. Fig. 13 = H. viii, 44. 

 " 2==H.iii,C.7. 8 = H.iv,69. 14 = H. viii, 4. 



3 = H. ii, 706, 9 =: H. iv, 33. 15 = 11. vi, 30. 



4 = H.i,143. 10 = H.iii,r.97. lG = H.vi,5. 



5 = H.iv,4. ll = H.ii,101. 17z^M.72. 



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



1815 105 293 A series of observations of the sateJUtes of the Georgian planet, including 

 a passae/e throur/h the node of their oMts ; with an introductory account 

 of the ieJescopic apparatus that has been nml on this occasion ; and a 

 final exposition of son.e calculated particuJars deduced from the obsernv- 

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



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



double power of magnifying and penetrating into space. 



294 The e/ccfu'C magnifying power defined. 



A 10-foot reflector, even with its highest powers, will not show these 



295 The machinery of my 20-foot telescope is so complete that I have 



been able to take up the planet at an early hour in the evening and 

 to follow it for 7, H, or 9 hours successively. The 40-foot telescope 

 h^s not been always used because time is required for preparations. 

 The temperature i's often too changeable ; its use requires 2 work- 

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



296 The 20-foot can be pointed on the planet with everything adjusted 



206 It'has'c™*ntiy been a rule with me not to observe with a larger 

 instrument when a smaller would answer. 



