Analysis of information sources in references of the Wikipedia article "Albert Brudzewski" in English language version.
First (about 1460) in Purbach's Theoricce nova Planetarum (ed. of Basle, 1573, p. 82) : "Ex dictis apparet manifeste, centrum epicycli Mercurij, propter motus supradictos non (ut in alijs planetis fit) circumferentiam deferentis circularem, sed potius figuras, habentis similitudinem cum plana ovali, peripheriam describere." Next by Albert of Brudzew in 1482 in his Commentariolum super theoricas novas, printed at Milan in 1495 (ed. Cracow, 1900, p. 124), where it is remarked that the centre of the lunar epicycle describes a similar figure. This is also stated by E. Reinhold in his commentary to Purbach, 1542, fol. P 7 verso (ed. of Paris, 1558, fol. 78); by Vurstisius in his Questiones nova in theoricas, &e., Basle, 1573, p. 233 ; and in Riccioli's Almagestum novum, T. i. p. 564. The last three writers (who give a figure) also take the equable angular motion round the centre of the equant into account, which centre lies on the point of the circumference of the small circle nearest the earth. The curve described by the centre of the epicycle thus becomes egg-shaped, and not like an ellipse.
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