THE Rev. Due Rojo, S.J., has an article within to, “En El Quarto Centenario Pel Nacimif Tie Tycho-Brahe” in Euclides of January 1046, N . 59, which, briefly outlines the main features astronomical work of Tycho Brahe. As a actical astronomer, Tycho realized that the question of the true system of the world could be ettled only by amassing evidence from the positions and motions of the planets. His long series of observations made possible the discovery of Kepler's laws of planetary motion and also the final proof of the heliocentric theory-a theory which Tycho himself had rejected. The author refers to his relations with astrology, and mentions one of his books which was published- after his death, with the expressive title, “Tychonis Brahe de disciplinis mathematicis oratio, in qua simul astrologia defenditur et ab objectionibus dissentien-tium vindicatur”. A similar vindication of astrology was the subject of one of his conferences in the University of Copenhagen, and his position at the Court required an annual compilation of prognostications for the year following as well as horoscopes of each member of the royal family. It is interesting to know that the foundation stone of Uraniborg was laid on August 8, 1576, at a time when Jupiter and Regulus were in conjunction and the moon was in Aquarius, that is, when the celestial influences were most favourable. Whatever may have been.the real views of some eminent astronomers on the subject, necessity sometimes compelled them to cast horoscopes as a means of livelihood. A well-known instance of this is seen in the case of Kepler, who cast horoscopes for princes and other important people. Probably astrologers in those days were able to ease their consciences by quoting the saying of the classical poet, “Mundus vult decipi: ergo decipiatur”. In spite of his astrological practices, Tycho stands before the world as a renowned astronomer and an example of what can be accomplished by patient and persistent observation.