7 
210 C. Abbe on the Repsold Portable Circle. 
to within two seconds of arc; or to be more definite, to within 
ing attention to the work of Colonel Smyssloff, mentioned below, 
where “are fully detailed the different astronomico-geographical 
methods of determining position, which, by the influence of the 
Poulkova Observatory, have been introduced into the geodetic 
work of the Russian empire, and which with perfect success sup- 
plant the far more tedious and costly triangulation.’* 
In the wilds of Central Asia and Siberia, as in some portions 
our own territory, preliminary surveys based on observations 
made with the pocket chronometer and Pistor and Martin’s pa- 
tent sextant, may supply our present need of information; but 
eastward to the Ural and Caucasus, it has been found practicable 
to transport the Repsold vertical circle and the Brauer’s extra- 
meridional transit. The methods of using these two instruments 
are fully given in the two following publications : 
Repsoldov Krug, Chronometri, Chronometretscheska Expedaitsir, 1859, goda. 
P. Smyssloff, S. Peterbourg, 1863. 
Die Zeitbestimmung, vermittelst des Tragbaren Durchgangs Instruments im Ver- 
ticale des Polarsterns, yon W. Déllen, St. Petersburg, 1863. 
A third memoir by Colonel Smyssloff (now Director of the 
Observatory at Wilna), 
Opuity dle oe 4 yer PT 
yteljnoi otsjenkay raslaytschnech sposoboff telegraphay-tscboskol 
ay vraymayne pray opredjelaynie rasnoste dolgote Poulkovskoi ay Mos- 
vskoi Observatorie. P. Smyssloff, St. Petersbourg, 1865, 
aunt. 
nations needed for the arc of 68° 54’ on the parallel of 52° north 
latitude. The surprising reliability of the portable transits made 
by Mr. Brauer, the mechanic of the Central Piserraln es now 
independently established in St. Petersburg, has shown them 10 
be anted to the highest requirements of the present state 
* Otto Struve, Jahresbericht, June 14, 1863, 
