Note 19 — LETTER V.

This information, I must acknowledge, is an exception to the generality of my assertion, for I do not believe it is contained in any of the elementary books I have mentioned; nor do I think it can be found in the writings of either Newton or Herschell, or that either of them, although so long engaged in examining the planetary system, were so fortunate as to observe any of these bodies at the moment when they were engaged in these friendly conversations. Perhaps the author has been led into a mistake by some obstruction in his glass, like a celebrated member of the Royal Society, who announced the discovery of an elephant in the moon, which, on examination, was found to be only a mouse in his telescope.