12 



MATHEMATICAL 



A ND 



move ia no other diredion than along the meridian • in 

 which are two marks South and North, about 710 ylrds 

 diftance each; to which it can be readily adjuftedin a hori- 

 zontal pofition by onefcrew as it can in a vertical pofition 

 by another fcrew. 



6. An excellent Time-Piece, having for its pendulum- 

 rod a flat fteel-bar, with a bob weighing about 12 lb. .and 

 vibrating m a fmall arch. It goes eight days, does not 

 Itop when wound up, beats dead feconds, and is kept in 



Mr. Rittenhoufc 



motion by a weight of jlb. 



Thefe three laft articles we 

 perty, and made by himfelf. 



7; ^" jftronomical ^adrant, two and an half f. radius, 

 made by Sijfon, the property of the Eajl Jerfey Proprie- 

 tors ; under the care of the Right Hon. William Earl of 

 Stirling, Surveyor-G^«^m/of that Province; from whom 

 Mr. Lukcns procured the ufe of it, and fent it up to Mr. 

 Rittenhoufc for afcertaining the latitude of the Obferva- 



Thus we were at length completely furniflied with 



tory. 



every inftrument proper for our work. 



As Mr. Rittenhoufe's dwelling at Norriton is about 20 

 miles North- Weft of Philadelphia, our other engagements 

 did not permit Mr. Lukcns, or myfelf, to pay much at- 

 tention to the neceffary preparations; but we knew that 

 we had entrufted them to a gentleman on the fpot, who 

 had joined to a complete (kill in mechanics, fo extenfive an^ 

 ajlronomical and mathematical knowledge, that the ufe 

 management, and even the conftrudion of the neceffary 

 apparatus, were perfedly familiar to him. Mr. Lukcns 

 and myfelf could not fet out for his houfe till Thurfday, 

 June ift; but, on our arrival there, we found every pre- 

 paration fo forward, that we had little to do, but to exa- 

 mine and adjuft our refpedlve telefcopes to dillina vif/on 

 He had fitted up the different inftruments, and made a 

 great number of obfervations, to afcertain the goina of his 

 Time-Piece, and to determine the latitude and lon<>itude 

 of his Obfcrvatory. The laudable pains he hath taken in 



thefe 



iT^-iU^ib^K 



