foeverj may be fpcedily made : which feemsto him mofl: 
^aficj becaufcj if itfuccecds, with one and the fame Tool 
may be ground an OhjeS Glafs of any length or breadth 
requifite j and that with very little or no trouble in fitting 
the Engin^ and without much skill in the Grinder. He thinks 
it very exadi:^ becaufe to the very laft ftroke the Glafs does 
regulate and redifie the Tool to its exaft Figure 5 and the 
longer or more the Tool Glafs are wrought together, 
the more exaft will both of them be of the defired Figure. 
He affirms further , that the motions of the Glafs and Tool 
do fb crofi each otherjthat there is not one point of eithers 
furface, but hath thoufandsof crofs motions thwarting it, 
fo that there can be no kind of Rings or Gutters made , ei- 
ther in the Tool or Glafs. 
5. A New Infirumenty by which the Refraction of all kinds 
of Liquors may be exadly meafured , thereby to give the 
Curious an opportunity of making Trials of that kind^, to 
cftabliflithe Laws of Refra&ion^ to wit, whether the Sines 
of the Angles of Refra&ion are reJpeSfivelj proportionable to 
the Sines of the Angles of Incidence : This Inftrument being 
very proper to examine very accurately , and with little 
trouble^and in finall quantities5the RefraBi9n of any Liquor, 
not onely for one inclination, but for all 5 whereby he is en- 
abled to make accurate Tables, By the fame alfo he af- 
firms to have found it true, that vAi^x. proportion the Sintoi 
the Angle of the one inclination has to the Sine of its Angle 
o{ Refra&ion ^ correfpondent to it, the lame proportion 
have all the other Sines of Inclination to their rcfpeftive 
Sines o(Refra&ions. 
Laftly, this Author dcfpairs not that there may be found 
many Mechanical Inventions,to improve our Senfo of Hea- 
ring.ySmelling^Tafling^ ToMching^2iS well as we have improved 
that of Seeing by Optick^ Glaffes. 
London, Printed with Licence {or John Martj/n^ SLud Jams 
Allefiry^ Printers to the Royal Society, 
