PHYSICAL AND MATHEMATICAL SCIENCES. 137

Of those attacks we have no satisfactory account;and it is not quite evident whether he refers to objec-tions actually made, or only apprehended. Certainlyno such objections emanated from the heads of the church,who were his friends and supporters; and he alludesto them only in a brief and somewhat contemptuousmanner. It was not till some time afterwards that wehave on record any systematic opposition to these viewsof the celestial motions, on the ground of alleged repug-nance to the truths of revelation.

The system advocated by Copernicus found at firstfew supporters ; hut the number, though small, in-cluded several of the most eminent philosophers of theday. The testimony given in its favour was that offew individuals, but of those best qualified to judge;and the adoption of the Copernican doctrine by thesemen was equivalent to its extended promulgation.

Such were Rhseticus, already mentioned, the authorof a commentary on the “ Revolutions,” and of extensivetrigonometrical tables ; Erasmus Rheinhold, who im-proved upon the astronomical tables of Copernicus ;and also taught that the orbit of Mercury is elliptical,and that the deferent of the moon is likewise elliptical;Rothmann, astronomer to William, landgrave of Hesse ;and Msestlin, the instructor of Kepler.

The landgrave of Hesse was a remarkable instance ofa sovereign prince devoting himself to the actual laboursof astronomical observation, and composing a catalogueof the fixed stars (156’0). He was assisted by Roth-mann, and also by Justus Byrgius , who directed con-siderable mathematical talents to the improved con-struction of the astronomical instruments, used by thelandgrave, in the superb observatory which he had erectedat Cassel. Msestlin was known by several astronomicalresearches. He availed himself of the principle of thecamera obscura to measure the apparent diameter of thesun by throwing his image into a dark room. He sug-gested the explanation now generally received of thefaint light visible on the dark navtof the moon, as being