Concerning the Efficacy of Monsieur de Villete his Burning Glass, all what the P. Bertet hath written of it, is true. We have seen the effects of it repeated over and over again, in the Morning, at Noon, and in the Afternoon, alwaies performing very powerfully; burning or melting any Matter, very few excepted. The Figure of it is round, being thirty Inches, and somewhat better in Diameter. On one side it hath a Frame of a Circle of Steel, to the end that it may keep its just Measure: 'Tis easie to remove it from place to place, though it be above an hundred weight, and 'tis easily put in all sorts of postures. The burning Point is distant from the Centre of the Glass, about three Feet. The Focus is about half a Louys d'or large. One may pass ones hand through it, if it be done nimbly; for if it stay there the time of a second Minute, there is danger of receiving much hurt.

Green wood takes fire in it, in an instant, as do also many other Bodies.

Seconds
A small peice of Pot-Iron was melted, and ready to drop down, in 40.
A Silver Peice of 15 Pence was pierced, in 24.
A gross Nail (called le Claude paisan) was melted, in 30.
The end of a Sword-blade of Olinde, was burn'd, in 43.
A Brass Counter was pierced, in 06.
A piece of red Copper was melted ready to drop down, in 42.
A peice of a Chamber Quarry-stone was vitrified, and put into a Glass-drop, in 45.
Steel, whereof Watch-makers make their springs, was found melted, in 09.
A Mineral-Stone, such as is used in Harquebusses à rovët, was calcin'd and vitrified, in 1. just.
A peice of Morter was vitrified, in 52.

In short, there is hardly any Body, which is not destroyed by this Fire. If one would melt it by it any great quantity of Mettal, that would require much time, the Action of Burning not being perform'd but within the bigness of the Focus, so that ordinarily none but small pieces are exposed to it. One Mounsieur de Alibert buys it, paying for it Fifteen hundred Livers.

Since this Information, there were, upon occasion given from thence, upon the same subject, further communicated from Paris the following Particulars.

I see by two of the Letters, that you incline to believe, the Glasses of Maginus and Septalius do approach to that of Lyons: But I can assure you, they come very far short of it. You may consult Maginus his Book, where he describes his; and there are some persons here that have seen one of his best, which had but about twenty Inches Diameter; so that this of Lyons must perform at least twice as much. As to Septalius, we expect the Relations of it from Intelligent and Impartial men. It cannot well be compared to that of Lyons: but in bigness; and in this case, if it have five Palms (as you say) that would be about 3½ feet French, and so it were a Foot bigger, which would make it half as much greater in surface: But as to the Effects, seeing it burns so far off, they cannot be very violent. And I have heard one say, that had seen it, that it did not set Wood on Fire but after the time of saying a Miserere. You may judge of the difference of the Effects, since that of Lyons gathers its Beams together within the space of seven or eight Lines;

and that of Septalius must scatter them in the compass of three Inches. Some here do intend to make of them yea and bigger ones; but we must stay till they be done, &c.

Of Monsieur Hevelius's Promise of imparting to the World his Invention of making Optick Glasses; and of the hopes given by Monsieur Hugens of Zulichem, to perform something of the like nature; as also of the Expectations, conceived of some Ingenious Persons in England to improve Telescopes.

That eminent Astronomer of Dantzick, Monsieur Hevelius, writes to his Correspondent in London, as followeth: