276 HERSCHEL. 
Practical astronomers know how much the mounting 
of a telescope contributes to produce correct observations. 
The difficulty of a solid yet very movable mounting, in- 
creases rapidly with the dimensions and weight of an 
instrument. We may then conceive that Herschel had 
to surmount many obstacles, to mount a telescope suit- 
ably, of which the mirror alone weighed upwards of 
1000 kilogrammes (a ton). But he solved this problem 
to his entire satisfaction by the aid of a combination of 
spars, of pulleys, and of ropes, of all which a correct 
idea may be formed by referring to the woodcut we have 
given in our Z’reatise on Popular Astronomy (vol. i.). 
This great apparatus, and the entirely different stands 
that Herschel imagined for telescopes of smaller dimen- 
sions, assign to that illustrious observer a distinguished 
place amongst the most ingenious mechanics of our age. 
Persons in general, I may even say the greater part 
of astronomers, know not what was the effect that the 
great forty-foot telescope had in the labours and discov- 
eries of Herschel. Still, we are not less mistaken when 
we fancy that the observer of Slough always used this 
telescope, than in maintaining with Baron von Zach (see 
Monatliche Oorrespondenz, January, 1802), that the co- 
lossal instrument was of no use at all, that it did not con- 
tribute to any one discovery, that it must be considered 
as a mere object of curiosity. These assertions are dis- 
tinctly contradicted by Herschel’s own words. In the 
volume of Philosophical Transactions for the year 1795 
(p. 350), I read for example: “On the 28th of August 
1789, having directed my telescope (of forty feet) to the 
heavens, I discovered the sixth satellite of Saturn, and I 
perceived the spots on that planet, better fhan I had been 
able to do before.” (See also, relative to this sixth satel- 
