SKECIMEN OF RESULTS OF LATITUDE OBSERVATIONS 



With Astronomical Transit* 

 (* ILLUSTRATED ON PAGE 189.) 



.Resulting Latitude 42 59' 58" 76 J 0".12. 

 Probable error of a single result J0".83. 



E. P. AUSTIN, OBSERVER. 



Plymouth, Mass., Oct. 16, 1888. 



Gentlemen : It gives me pleasure to call your attention to some unexpected results obtained Aug. 39, 

 1888 with the4-inch transit* lately made by you for the Massachusetts Topographical Survey Commission. A 

 triangle lying across Herring Pond on the line of Plymouth and Barnstable Cos. was selected, all the angle? 

 were measured under nearly the same conditions of light and temperature. The instrument was protected fron, 

 Bun with a large white carriage umbrella. 



The method followed in observing, was to set the instrument at o and then repeat the angle 6 times 

 repeating from left to right. Then the outside angle was measured in the same direction with same number of 

 repetitions thus filling the circle. The inside angle was then corrected by one-half the error of the filling of 

 the circle giving the weight to the angle of 12 pointings. I then set at 90 and repeated the operation set 

 accompanying sketch. The other two angles of the triangle were treated in the same manner. 



AT NOTICE. 



Setting at Parker and Old Board (6 Reps.) 33 23' 22^.9 + 0".4 = 23".l 

 Old Board and Parker ( " ) 326 36 36 .7 



59" 6 



" 90 Parker and Old Board ( " ) 33 23' 22".l 4- 1".4 23".l 

 Old Board and Parker ( " ) 326 36 35 8 



57".9 



AT PARKER. 



Setting at Old Board and Notice (6 Reps. ) 68 27' 37".5 0".4 = 37". 1 



Notice and Old Board ( 



291 32 23 .3 



NOTICr. 



90 Old Board and Notice ( 

 Notice and Old Board ( 



) 68 27' 37". 1 / .4 // = 36". 1 

 ) 291 32 23 .8 



00".9 



AT OLD BOARD. 



Setting at Notice and Parker (6 Reps.) 78 09' 02".l 1".6 = 00" .5 

 Parker and Notice ( " ) 281 51 01 .2 



Notice and Parker 

 Parker and Notice 



" ) 7809'00".8 0".8 

 00 .7 

 01".5 



Triangle. 



Setting at Notice 33 23' 23".l 



Parker .... 

 Old Board . 



^00".0 



PO 



68 27 36 .9 

 78 09 00 .2 



18000 / 00".2 



The mean difference of the two sets at each station was o".3o the greatest difference being o" eo Th 

 Bean corr. for the three circles was o". 33 . The triangle filled 180 oo / oo".2. I had no difficulty in readinc 

 the limb to 20". Heretofore, I have looked for such results from a lo-inch Gambey. This is the only triamr'* 

 1 nave examined, but we have repeatedly obtained results of combined angles equally gratifying 



Very respectfully, C. H. VAN ORDEN 



* The Instrument referred to is the No. 4, Transit, described on pp. 160 and 161. 



