ascent and descent of the stars etc., from the vast ocean 

 of the heavens, catching the straight ascent in the 

 greatest circles and, in other unequal circles, parallel 

 to each other and obliquely cutting across, most safely 

 catching the descent. 



Immediately below the Primum Mobile place the 

 heaven of the fixed stars (and, that the idea mighl be 

 clearer), revolving separately on the same poles on which 

 the Primum Mobile revolves. Through this heaven, the 

 filaments of the little nets, etc., seem to the eyes of you on 

 earth as if they shine. In this heaven, you should 

 conceive in their fixed places, the fixed stars, a propor- 

 tionate, inviolable distance from each other, and, indeed, 

 if you will, the heavenly images, etc., depicted, and all 

 carried along at the same time with their heaven l>\ one 

 motion. 



Conceive a straight line running from the center of the 

 earth to that sign "o" noted in the semicircle of the 

 supreme immobile heaven. On this line, greatly below 

 the heaven of the fixed stars, place the center of the solar 

 epicycle, holding an area in common with the ecliptic 

 and subject to absolutely no motions, but at such a 

 distance from the center of the earth that the semi- 

 diameter of the earth has little, if any, proportion with 

 the distance of the solar epicycle from the earth. Around 

 the sun, moving continually in this epicycle (its immobile 

 palace) through the degrees of the anomaly, you cm 

 revolve, with motions proportionate to the system, the 

 five planets: Mercury and Venus (the nearest barons of 

 the sun), then Mars, Jupiter and, most remote, Saturn, 

 with its respective satellites, etc., excentrically surround- 

 ing the earth itself and the moon in their immense ambit 

 and wandering by their proper motions through the 

 zodiac. 



Nevertheless, not far from the earth you should imagine 

 fabricated, as from most refined crystal, the heaven of the 

 moon everywhere equidistant from the center of the 

 earth and revolving separately on the same poles (pro- 

 longed even to this place) on which the Primum Mobile 

 and the heaven of the fixed stars revolve. In the middle 

 of this, that is, in some point equally removed from the 

 poles, you place the center of the 1liii.ii epi< y< le, movable 

 also by the common rotation of the lunar heaven. I 

 refrain from I he other movements of the moon in latitude. 

 etc., as also those of the five planets, etc., which the 

 theory in no way excludes, lest by a variety of congested 

 motions explained too abundantly, either you might be 

 i onfused about the fundamental concept of the system or, 

 while adorning the theorj and trying to embellish the 

 least things more widely, you might reject also the 

 things which are capital. 



Here you already have the whole machine, but still 

 inert and to be animated for the first time In motions 



iiiuiod.iicil to the system, \evei thi-less, before 1 



assign motion to the individual pails of the world, so 



that the thing might later appear more clearly to you, I 

 arrange all things thus: first, as if by hand, I turn the 

 Primum Mobile until the Boreal magnetic point comes 

 to the level or the area of the semicircle described in the 

 supreme immobile convexity; then I turn the heaven of 

 the fixed stars until, for example, the heel of Castor 

 (a star of the third magnitude), almost in the ecliptic 

 and indeed in our time not far distant from the solstitial 

 colure, likewise falls nearly at the level of the aforesaid 

 semicircle. Later, I turn the lunar heaven until I bring 

 the center of the lunar epicycle to the same level. Then. 

 I turn the earth until some predetermined city, for 

 example, Trent, situated in the northern zone with a 

 latitude of about forty-six degrees, is brought to the 

 oft-mentioned level. 



From things arranged in this way and from what has 

 gone before, it is evident (with the motions of the 

 luminaries in epicycles left out, however, lest you be 

 distracted by the explanation) that at Trent, just as 

 in the whole northern hemisphere, it is the summer 

 solstice; and, conversely, in the southern hemisphere, 

 it is the winter solstice. The reason is because the 

 northern magnetic point together with the northern half 

 of the earthly axis is at its highest point towards the sun, 

 immovably residing in a line sent through the level of 

 the highest semicircle; and, conversely, the southern 

 magnetic point with the corresponding half of the 

 axis is most removed from the same. It further follows, 

 that noonday and the new moon coincide, and the heel 

 of Castor almost reaches the summit, etc. 



Now, beginning from this hypothetical situation of 

 the whole world as from the root of the motions, I move 

 all things in their circles so than the earth turns on its 

 axis with a revolving motion from west to east in each 

 24 hours of median time. The lunar heaven completes 

 one circle around its poles likewise from west to east in 

 the time of 29 terrestrial revolutions, hours 12. 44. 3. 13. 1. 

 The sphere of the fixed stars on the same poles revolves 

 once from east to west within 365 revolutions of the 

 earth, hours 6.9.29.1. The Primum Mobile on the poles 

 (common to the heaven of the fixed stars and the heaven 

 of the moon), is moved once in the same way from east 

 to west, a little faster, however, than the heaven of the 

 fixed stars, yet within 365 revolutions of the earth, hours 

 5.48.56; that is, within a median astronomical year. 



Now, behold for yourself a new world supported on new 

 poles and provided with new motions and laws. Now 

 you, reader and lover of the stars, turn it, and revolve 

 it as long as it pleases you, and compare it astronomically 

 and physically with the Copernican or the Tychonian 

 systems or with whatever one pleases you more, and 

 judge which one seems more consonant with nature 

 when all things are examined. But if you aren't able to 

 reconcile this theory with some astronomical observa- 

 tions or physical experiments and think it should be 



56 



II I I I TIN 240: CONTRIBUTIONS FROM THF MI SI IM OF HISTORY AND TECHNOLOGY 



