The CONTENTS.

3. ttherwise 3 IjCM. Slusinj Pag. 174

4. Otbermifc 3 by CM. Hugens 177

5. Furtber confidcr'd ; by CM. SIusius I 78

6 . ByCM. Hugens 180

7. By M. SI alius '182

X. Tofind thi Principal Focus«/. OptiC^GLtTesuniversal !)/; by Mr. Edm. Halley 183

XI. i. Jht Generation of an HyperbolicalCvlindroid \ .by Sir Christ. Wren 188

2. Ihe Application thereof to the Grinding ofHyperbolical Optic Glaffes3 by Sir Chr.Wren ir9

XII. Why Four Convex Giajsis in a Teleskope

fern Objetts Ereil : by CMr. VVilliam Moli-ne ux ibid.

XIII. 1. The Apertures of Telefcopes^ by

CM. Auzout 191

2. Confidcr'd 3 by Dr, Hook 192

XIV. To measure Diftances at One Station-,

by CM. Auzout ibid,

XV. To make a Plano-Comex Ghfs of t fmali

Spiere, colletttbe gays at agreat D/stance ;by Dr, .Hook 193

XVI. 1. Telescopes ftnd other Optic-Glaffes 3

£7 Campani and Divini ibid.

2. ByCM. Hcveliustf »4 CM. Huygens ibid.

3. By Od. du Sons ibid.

4. ByCM. ßuratcini 194

5. By CMr. Frar.cisSmethwick ibid.

6 . By an ArtiH tt Paris ibid.

7. By Od, Boielli 195

8. 0 ,‘tick Lent's of Reck-Christas by Eust.

Di'ini ibid

9 Of Water ; by Odr. Stephen Gray ibid.

XVII. t. The Advantag s of Reflexion to O t >-tic Inßruments ; oy CMr. Newton 19^

2. A New Citadioptucul Teleicop-; in. - n-tedby Odr. NiWCon ,9

z. Approv’d^ by Od. Huygens de Zulithen

'99

4. Afunber Account of tbis Instrument-, A«CMr. Newton ,l i

$. The Aper’ures, andC h a rges of thrj. ,<struments\ ly CMr N w«on ?.r

XVIII. 1. Sem Oojedicn of M. An

fmer'd byOdr. Newton Jot

2. The Considerationi of ..... Anfvtcr’d by

CMr. Newton 2c 2

3. Objettions by M. 203

Anfwer'd : by CMr. Newton . ibid.

4. A geplyt, by M. joj,

Anjreer'd 3 by Mr. Newton ibid,

XIX. 1. A Catadioptrical Telescope; by CM.

Cassegrain ibid.

2. Consider'd 3 by CMr, Newton ibid.

XX. A Catadioptrick Telescope 3 by S. Sal-

vetei 202

XXI. 1. To male the Pishire of any thing ap-ptarin a Light Room ; by Dr. Hook. ib.

2. Ihe Magic Lanthorn improv'Jy by SirRobert South*el 207

XXU. A Way to help Short Sightedness 3 by

Dr. Hook ibid.

XXIII. 1. Microscopes-, by S. Diyini ibid.2. By S. Pier. Salvetti 208

z. By CM. Leeuwenhoeck ibid.

4. By CMr. Butterfield ibid.

By CMr. Stephen Gray ibid.

XXIV. 1. A Water-Microscop«; by Mr.Stephen Gray 209

2. An other ibid.

XXV. Microscopes improiftl 3 by Odr. New-ton 210

XXVI. 1. A Reflectnig Microscope ; by Mr.Newton ibid.

2. By CMr. Stephen Gray 211

XXVII. I. A Burning Concave L» Lyons3müde by CM. de Viletce ibid.

2. Anotber bytbe samt 212

3. By S. Settela. ibid.

4. A Buining Concave in Germanyj by

..... 213

5. Bt Dr. Hook ibid.

XXVI! ‘. C neave Specula, nearly of -r Para-

tfc : 1 F gure 3 attempted by Mr. StephenG a, 214

x aiX. ‘o ■nake the Globe Looking-Glais; bySir R -bert S üthwel ibid

XX. Faveri Ommed 215

aXXJ. Account! of Boolts Omicted ibid.

C H A P. IV.

jistronomy.

I. r P H E Observatory of Tycho Brache 3

1 by Mr. Gourdon Pag. 216

II. A New Astronomica! Instrument 5 by Qd.

Weighelius ibid.

III. A Celestial Globe 3 £7 M. Didier l’Aüe-

man ibid.

IV. A Way to rnafure the Diameters of the

, Ptenets,