“ And for making spherical Glasses by an Engine, I am apt to think, there hardly can be any way more plain, and more exact, than that which I have described; wherein there is no other motion, than that of two such Mandrils, which may be made of sufficient strength, length, and exactness, to perform abundantly much more, than I can believe possible to be done otherwise than by chance, by a man's hands or strength unassisted by an Engine, the motion and strength being much more certain and regular. ”

“ For, the same Glass will endure greater or lesser Apertures, according to the lesser or greater Light of the Object: If it be for the looking on the Sun or Venus, or for seeing the Diameters of the Fix'd Stars, then smaller Apertures do better; if for the Moon in the daylight, or on Saturn, or Jupiter, or Mars, then the largest. Thus I have often made use of a 12 foot Glass to look on Saturn with an Aperture of almost 3 inches, and with a single Eye-glass of 2 inches double convex: but, when with the same Glass I looked on the Sun or Venus, I used both a smaller Aperture, and shallower Charge. ”

“ Touching the quantity of Light, which a Body, that is 10. 15 and 20 times, &c. remoter than Saturn, would yet receive from the Sun. 2. Touching the quantity of Light, by which the Earth is illuminated even in the Eclipses of the Sun, in proportion of their bigness. 3. Touching the quantity of Light, which is necessary to burn Bodies: he having found, that not abating the Light, which is reflected by the Surfaces of the Glass (whereof he confesseth, he doth not yet exactly know the quantity) there would be necessary about 50 times as much Light, as we have here, for the burning of Black Bodies ”

“ Whether the Blood affords both the Matter for the structure of the Body, and such parts also, as are fit for the nourishment of the same? Whether the Pulse of the Heart ceasing, there remains yet a certain Motion in the blood, arguing, that Pulse and Life do ultimately rest in the Blood? ”

“ He adds, that it is very difficult to contrive, that the middle of the Glass do always precisely answer to the Brim of this Ring, seeing that the position of the Glass does always change a little in respect of the Ring, in proportion as 'tis worn, and as it must be pressed because of its inclination. He believes it also very hard, to give to the Axis or to the Mandril which holds the Glass, that little Inclination, that would be necessary for great Glasses, and to make the two Mandrils to have one and the same Plain, as is necessary. ”

“ And if any weight or Engine be used to supply strength, there is then danger of an unequal pressure, and of wearing away the Engine; In the mean time, the preciseness and delicateness is greater than can easily be imagined. Wherefore he could never, having some experience of this preciseness, conceive, that a Turn-lathe, wherein must be two different, and in some manner contrary motions, can move with that exactness and steddiness, that is required, especially, for any considerable length of time. ”

“ Which difference yet dos not appear to M. Auzout to be so great; but that M. Hugens perhaps will impure it to the Optical reason, which he (Auzout) hath alleged of the Advance of the light upon the obscure space; although he is of Opinion, he should not have concluded so great a Length, if he had not seen the Breadth spread out more, than he hath done: for (saith he) if the Length of the Ring be to the body of Saturn, as 21/2 to 1. and the Inclination be 23 deg. 30′ the Ring will be just as large, as the body, without spreading out; but if the Ring be bigger, it will a little spread out ”

“ He notes also, that the Eye-glass of the said Telescope, composed of 2 Glasses, hath no more effect, when it is most charged, than a Glass of 41/2 inches; which makes it magnifie not a 100 times. And he finds by Mr. Hook, that he esteems a Telescope made in London of 60 feet, (which amount to about 57 feet of France, the foot of France being to that of England as about 15 to 16) because it can bear at least 3 English inches Aperture, and that there are few of 30 feet, that can bear more than 2 inches, (which is but 221/2 Lines French) although he (M. Auzout) gives no less Aperture. ”

“ And indeed, for any man to look upon the matters published by their Order or Licence, as if they were Their Sense, and had Their Approbation, as certain and true, 'tis extremely wide of their intentions, seeing they, in giving way to, or encouraging such publications, aim chiefly at this, that ingenious conceptions, and important philosophical matter of Fact may be communicated to the learned and enquiring World, thereby to excite the minds of men to the examination and improvement thereof. ”

“ Hence he also taketh occasion to intimate, that we need not scruple to conclude, that if these two Planets have Moons wheeling about them, as our Earth hath one that moves about it, the conformity of these Moons with our Moon, does prove the conformity of our Earth with those Planets, which carrying away their Moons with themselves, do turn about the Sun, and very probably make their Moons turn about them in turning themselves about their Axis ”

“ And though M. Auzout seems to find fault with the English Glass of 36 foot, that had an Aperture of but 23/4 inches French, as also, with a 60 foot Tube, used but with an Aperture of 3 inches; yet I do not find, that he hath seen Glasses of that length, that would bear greater Apertures, and 'tis not impossible, but his Theory of Apertures may fail in longer Glasses.
Of a means to illuminate an Object in what proportion one Pleaseth; and of the Distances requisite to burn Bodies by the Sun. ”

“ That great Optick Glasses have almost never as great an Aperture as the small ones, in proportion to what they Magnifie, and that therefore they must be more dim; takes occasion to inform the Reader, that he hath found, that the Apertures, which Optick Glasses can bear with distinctness, are in about a subduplicate proportion to their Lengths ”

“ Hook, and found there, that his Engine was published upon a meer Theory, without having made any Experiment, though that might have been made with little charge and great speed; expence of Money and Time being the onely thing, that can excuse those who in matter of Engines impart their inventions to the publick, without having tried them, to excite others to make trial thereof. ”

“ Hook (adds he) did use but his Ring of 6 inches, which he would use from twelve to an hundred foot Glass, the Inclination, which the Axis, or Mandril, that bears his Glass, should have, should be but 16 minuts, and the Curvity of the Glass would be less than the eighth part of a Line, and if he should use a bigger; the Inclination would be proportionable.
Whence it may be judged (continues he) that we are yet very far from seeing Animals &c. in the Moon, as Monsieur Des Cartes gave hope, and Mr. Hook despairs not of. ”

“ For, he believes by what he knows of Telescopes, that we are not to look for any above 300 or 400 foot at most; and he fears, that neither Matter nor Art will go even so far.
When therefore (saith he) a Glass of 300 foot should bear an Eye-glass of 6 inches (which would appear wonderful) it would magnifie but 600. times in Diameter, that is, 360000 times in Surface: but suppose, that such could be made, as would magnifie a 1000 times in Diameter, and 1000000. ”

“ Upon the West side of the Long Island, the Tides, which came from the South-west, run along the Coast, Northward; so that during the ordinary course of the Tides, the Flood runs East in the Frith, where Berneray lyes, and the Ebb West. ”

“ All which particulars, he conceives to be very hard in the practice; not to mention, that the weight of the Glass, that should be inclined to the Horizon, as 'tis represented by Mr. Hook, would make it slide upon the Cement, and so change the Center; and that the Glass is not pressed at the same time by the Ring but in one part on the side, vid. about a fourth; and that the parts of the Glass are not equally worn away, &c. ”