ASTRONOMICAL PAPERS. 



II 



>9 



" name to the college — Meffrs. Mafon and Dick/on tell me, 

 *' they never ufed a better than that* which I formerly 

 " fent to the Library Company of Philadelphia, with 

 " which a good obfervation may be made, though it has 

 *' no micrometer. 



We were now enabled to furnifli the Nbrriton Obferva- 

 tory, as follows, i;zz. 



i^ A Gregorian ReJleSIor about 2 f. focal length, with 

 2iDoUond\ Micrometer. ThisTelefcope hath four different 

 magnifying powers, viz. 55, 95, 130, and 200 times; by 

 means of two tubes containing eye glaffes that magnify 

 differently, and two fmall Speculums of different focal 



diftances. Made by Nairne. 



Ufed by Dr. Smith. 



2. A RefraBor of 42 f, its magnifying power about 

 140. The glafles were fent from London with the large 

 Reflector, and belonged to Harvard College, New-Eng- 

 land; but as they did not arrive time enough to be fent 

 to that place before the Tranfit, they were fitted up here 

 by Mr. Rittenhoufe\ and ufed by Mr. Lukens. 



3. Mr. Rittenhoufe*s RefraSlor^ with an objed: glafs of 



36 f. focus, and a convex eye glafs of 3 inches, magnify- 



ing about 144 times. 



Ufed by Himself. 



Both thefe Refradors, as well as the Reflcdor, wxre in 

 mofl: exquifite order. 



4. An Equal Altitude Inftrument-, its tclcfcope three and 

 . an half feet focal length, with two horizontal hairs, and 



a vertical one, in its focus, firmly fupported on a ftone 

 pedeftal, and eafily adjufted to a plummet wire 4 feci in 

 length, by 2 fcrews; one moving it in a' North and South, 

 the other in an Eaft and Weft direftion. 



5. A Tranfit Telefcope^ fixed in the Meridian on an axis 

 with fine ftcel points; fo that the hair in its focus can 



move 



* Mr. Owen Biddt-r, who was appointed by the Society to condutil the obfervation near 

 Cape Henlvpen^ had this teleicoptf, ; nothing being dcfired there but x)nc contaSis and their exa<il 

 time; which he obtained to great latisfaiilion, as by liis report may appear. As he had but 

 fliort time to prepare, and there war, a diificulty in gettinj^ the ncceffary apparatus for fixing, by 

 his own obfervations, the longitude and latitude of the place choien for his ftation, itwagre- 

 foived to depend on the afcertaining thefe articles, by running a line from the place of his ob- 

 fervation to a known point in the work of Melfrs. Muf».i and Dixofty when employed in fet- 

 tling the boundary hnes of FaiufyliHuiia and Maryland; and in nieafuring a degree of latitude^ 

 along that fine level peniufula, between Delaivar: and Chcfaptdk Says, 



