sir CHRISTOPHER WREN, knt.

ttiean while to suggest to your Lordship I cannot guess; the Solemnity of theOccasion, and my Solicitude for the Honour of the Society, makes me thinkNothing proper, nothing remarkable enough. ’Tis not every Year will producefilch a Master-experiment as the ‘Torricellian , and so fruitful of new Experi-ments as that is, and therefore the Society have deservedly spent much Timeu pon that and its Offspring: And if you have any notable Experiment thatmay appear to open new Light into Principles of Philosophy, nothing wouldgetter beseem the Pretensions of the Society , though possibly such would be tooJ e june for this Purpose, in which there ought to be something of Pomp: Onfile other Side, to produce Knacks only, and Things to raise Wonder, such asKercber, Scottus, and even Jugglers abound with, will scarce become the Gra-bty of the Occasion : It must therefore be something between both, luciserousPhilosophy, and yet whose Use and Advantage is obvious, and without alecture; and besides may surprize with some unexpected Effect, and be com-mendable for the Ingenuity of the Contrivance. Half a Dozen of Experimentsfiius qualified, will be abundantly enough for an Hour’s Entertainment; and* cannot believe the Society can want them, if they look back into their own^ore. For myself, I must profess freely, I have not any Thing by me suitableto the Idea I have of what ought to be perform’d before such an Assembly.Geometrical Problems, and new Lines, new Bodies, new Methods, how ufe-fiil soever, will be but tailless in a transient Show. New Theories, or Ob-Wations, or astronomical Instruments, either for Observation or Facilitationthe Calculus, are valuable to such Artists only who have particularly expe-mriented the Defects that these Things pretend to supply. SciographicalJCtiacks, of which yet a hundred Varieties may be given, are so easy in themvention, that now they are cheap.- Scenographical, Catoptrical, and Diop-fdcal Tricks, require excellent Painting, as well as Geometrical Truth in ther ofile, or else they deceive not. Designs of Engines for Ease of Labour, orPfomoting any Thing in Agriculture, or the Trades, I have occasionallysought upon divers, but they are not intelligible without Letters and Referen-ts, and often, not without something of Demonstration. Designs in Archi-tecture, &c. the few chymical Experiments I have been acquainted with,Mil, I fear, be too tedious for an Entertainment. Experiments in Anatomy,fiio of the most Value sot their Use, ate sordid and noisom to any but thoseMiose Desire of Knowledge, makes them digest it. Experiments for the Esta-"Jissiment of natural Philosophy are seldom pompous; ’tis upon Billiards, andlennis-Balls $ upon the purling of Stick? and Tops; upon a Viol of Water,0r a Wedge of Glass, that the great Des Cartes hath built the most refined?ld accurate Theories that human Wit ever reach’d to; and certainly Naturethe best of her Works is apparent enough in obvious Things, were theyOct curiously observ’d; and the Key that opens Treasures, is often plain and^sty, but unless it be gilt, ’twill make no Show at Court.

, If I have been conversant in philosophical Things, (as I know how idle I^Ve been) it hath been principally in these Ways, which I have recountedyour Lordship, by which your Lordship perceives how useless I am for thiser vice; yet if your Lordship will still pursue me, I know not what Shift to^ake, but to retire back to something I have formerly produe’d.

I have pleas’d myself not a little with the Play of the Weather-wheel, (the°?Iy true Way to measure Expansions of the Air) and I imagine it must needsothers Satisfaction, if it were once firmly made, which, I suppose, may bectct, if the circular Pipes (which cannot be truly blown in Glass) were madeI Brass, by those who make Trumpets, and Sackbutts, (who wire-draw theiripes thro' a Hole to equal them, and then filling them with melted Lead,Ul ' n them round into what Flexures they please) the Inside of the Pipe must

m be