156 Suggestions for Observation 



Schuscha, are within the southern boundary : that Frieder- 

 ichsvam, Goteborg, Carlskrona, Kalmar, Danzig, Ostro- 

 lenka, Lonija, Bialystoek, Brest-Litowsk, Jitomir, Mach- 

 nowka, Lipowez, Uman, Babrinez, Jenikale, Tiflis, Schemacha, 

 are nearly on the central line : that Christiania, Friederich- 

 stadt, Konigsberg, Gumbinnen, Augustowo, Grodno, Slonin, 

 Pinsk, Radomist, Kiev, Jelisawetgrad, Berdiansk, Stavropol, 

 Gheorgiewsk, Wladikawkas, are within the northern boun- 

 dary : and that Carlstad, Memel, Tilsit, Krementschug, Eka- 

 terinoslav, Mariupol, Mosdok, Derbent, are at a small dis- 

 tance beyond the northern boundary. 



4. Now it appears extremely desirable that, if possible, 

 observers should arrange themselves in confederations, each 

 confederation consisting of three directing- astronomers, who 

 should by concert station themselves at three places respec- 

 tively near the northern boundary, near the centre, and near 

 the southern boundary ; these places being not very widely se- 

 parated in the longitudinal direction of the shadow's movement. 

 Thus Arendal, Friederichsvarn, Christiania ; Kulm, Danzig, 

 Konigsberg; Warsaw, Ostrolenka or Lomja, Augustowo; 

 Brody, Brest-Litowsk, Grodno ; Nikolaiew, Babrinez, Jelisa- 

 wetgrad, &c., would be favourable combinations. Two or 

 three such confederations should be formed at different parts 

 of the shadow's path. 



5. It is desirable that, at each station, there should be 

 three or four observers. One should be furnished with a 

 telescope magnifying about twenty times, with a pretty large 

 aperture ; and this will probably be found the most important. 

 A second should have a telescope magnifying 100 times. 

 Each of these telescopes should have in its field, but not 

 crossing the centre, two wires of an interval of T, or some 

 other convenient distance, for giving an approximate measure 

 of any small object which may be observed. It is desirable 

 that by the position of these wires, or in some other way, the 

 observer should be able rapidly to refer the positions of 

 objects seen in the telescope to vertical and horizontal di- 

 rections. A third person should have a watch or chrono- 

 meter (if the error of the chronometer is known, the astro- 

 nomical value of the observations will be increased, but their 



