. ( 787 ) 
in acSis Lipfienfibus & alibi reperiuntur, quam pra^flantiffi- 
mus il]e liber (cni Titulum dedit Analyfe des Infini' 
went ptits) faciunt ut magna quasq; ab Eruditiffimo Marchi- 
one expedemus. 
Quodque ingeniofiflinio Jo, Bernoullio vifum fuerit ( in 
Adis Anni i6<^^. Menfibus Febr. 8c Auguft:) Mcthodum 
meam non effe generalem pronunciare^ id etiam ego lubens 
agnofco, ut exemplorum meorum ferie facile percipere po- 
tueric Vir acutiffimus. In materia difficili gradus, quos po- 
teranij feci ; 8c fi itineris Longicudine vel difficultate deter- 
ritus non ulterius tarn progreffus fuerim, mihi tamen (qui obi- 
ter tantum fiudiis hifce Mathematicis Animum adhibeo) qua 
volui, fiftere licebat. In quo baereat Method us mea parrim 
notavit clariff. BernoulHus ; rem tamen toram non prorfus 
affequutus videtur. Interim illi me plurimum devin<5lum ha- 
beo, quod fua Animadverfione Tradatum meum dignatus fu- 
erit, multo tamen magis, quod tarn candide, tamq; humane 
me ab erroribus meis liberate voluerit. 
VL A Letter from Mr. Stephen Gray, dated 
Canterbury , Dee. 8» i^pj. relating fame 
Experiments about making Concave Specula 
nearly of a F arabolic\Figure» 
I Had before this time communicated the Experiment 
I mentioned in the end of my Letter of the 12th of 
May Jaft, had I not expefted an Opportunity to have 
made fome farther Progrefs than I have yet done. I 
lhall not fpend time to teli you how I have been obftru- 
died in having my Thoughts diverted by other 
Affairs , yet I think it convenient to let the Soci- 
ety knov^ how far I have proceeded toward the way 
to make the Concave Specula nearly of a Parabolick 
Figure, which they will naturally receive, or at leaft 
with a very little Affiftance of Art, having the Ambiti- 
on to think, that if any ingenious Perfbn Iball tliink fit 
to-: 
