Christiani Hugenii Zelemii, dum viveret, toparchae opuscula postuma, quae continent dioptricam. Commentarios de vitris figurandis. Dissertationem de corona & parheliis. Tractatum de motu. De vi centrifuga. Descriptionem automati planetarii

between the Earth and Mars than between the latter and Venus; and also because the toothed ring becomes larger in this way and therefore accommodates larger teeth, and finally because in this way it achieves with two wheels what is done in the Automaton with three.

We found deep silence in this description regarding Mercury; therefore, it was necessary to add its constitution, which was drawn from an inspection of the Automaton itself and from certain dispersed notes of the Author. The same has been done regarding the cause of the inequality of motion, and regarding the definition of the amount of aberration by which this machine deviates slightly from the true proportion of celestial motions.

These are the things about which we thought it necessary to warn you briefly. Furthermore, we have no doubt that if it had been permitted for the Author himself to give these little works their final polish, everything would have been many parts more accurate and perfect. We have done what we could. We have certainly endeavored to accommodate ourselves to the Author's sense. If we have succeeded, we have cause to congratulate ourselves; but if we have suffered any human failing, we hope for indulgence from the fair Reader, especially if they weigh how much labor and tedium it is to scrutinize the thoughts of another. Farewell.