ous rayes, nor can this their inadvertency be excused, in regard that it was in their power to have beheld them at their pleasure without those tresses, which is done, by looking upon them at their first appearance in the evening,Venus renders the errour of Astronomers in determining the magnitudes of stars inexcusable. or their last occultation in the comming on of day; and if none of the rest, yet Venus, which oft times is seen at noon day, so small, that one must sharpen the sight in discerning it; and again, in the following night, seemeth a great flake of light, might advertise them of their fallacy; for I will not believe that they thought the true Discus to be that which is seen in the obscurest darknesses, and not that which is discerned in the luminous Medium: for our lights, which seen by night afar off appear great, and neer at hand shew their true lustre to be terminate and small, might have easily have made them cautious; nay, if I may freely speak my thoughts, I absolutely believe that none of them, no not Tycho himself, so accurate in handling Astronomical Instruments, and that so great and accurate, without sparing very great cost in their construction, did ever go about to take and measure the apparent diameter of any Star, the Sun and Moon excepted; but I think, that arbitrarily, and as we say, with the eye, some one of the more antient of them pronounced the thing to be so and so, and that all that followed him afterwards, without more ado, kept close to what the first had said; for if any one of them had applied himself to have made some new proof of the same, he would doubtlesse have discovered the fraud.
Sagr.But if they wanted the Telescope, and you have already said, that our Friend with that same Instrument came to the knowledge of the truth, they ought to be excused, and not accused of ignorance.
Salv.This would hold good, if without the Telescope the businesse could not be effected. Its true, that this Instrument by shewing the Discus of the Star naked, and magnified an hundred or a thousand times, rendereth the operation much more easie, but the same thing may be done, although not altogether so exactly, without the Instrument, and I have many times done the same, and my method therein was this. I have caused a rope to be hanged towards some Star,A way to measure the apparent diameter of a star. and I have made use of the Constellation, called the Harp, which riseth between the North and ** Rendred in Latine Corum, that is to say, Northwest. North-east, and then by going towards, and from the said rope, interposed between me and the Star, I have found the place from whence the thicknesse of the rope hath just hid the Star from me: this done, I have taken the distance from the eye to the rope, which was one of the sides including the angle that was composed in the eye, and ** i.e. Is subtended by. which insisteth upon the thicknesse of the rope, and which is like, yea the same with theangle
