June 12, 1903.] 



SCIENCE. 



949 



of M. Gonnessiat at the observatory for the 

 determination of the longitiide of the second- 

 ary stations. For this purpose M. Maurain, 

 before starting, determined his difference of 

 personal equation with M. Gonnessiat and 

 then determined the difference of longitude 

 between Quito and the two secondary stations, 

 on three evenings, using one ehonograph in- 

 stalled at Quito which registered the observa- 

 tions of the two observers. Telegraphic com- 

 munication was made without a relay. The 

 latitude of Tacunga was determined on four 

 evenings with a meridian circle and the pre- 

 liminary general mean is 0° 56' 00".97. The 

 results of the observations for altitude at 

 Ibarra are not yet reduced. 



Geodetic Operations. — The astronomical ob- 

 servations have been completed and the un- 

 expected delay has all been in the geodetic 

 work. 



The northern section from the side Zagroun 

 Lanlanguzo includes thirty stations between 

 the two base lines, and of these thirty stations 

 only six or seven remain to be occupied. 



The northern observing party has com- 

 pleted the polygon which encloses the El 

 Vinculo base line, except the central station 

 Machines, while the southern party, starting 

 from the line Zagroun-Lanlanguzo to the 

 south of Eiobamba, has reached the line 

 Pichincha-Pambamarca, to the north of Quito. 

 Unhappily we must expert to find difficulties 

 at the remaining stations, similar to those , 

 already encountered, on account of the cli- 

 matic conditions. 



The azimuths already determined show a 

 very satisfactory agreement and the mean 

 error of closure of the triangles already com- 

 puted is about one second. 



Zenith Distances. — In general, it is not pos- 

 sible to measure simultaneous reciprocal 

 zenith distances, but reciprocal zenith dis- 

 tances have been obtained between all the sta- 

 tions. The preliminary examination of these 

 observations shows that they are very accord- 

 ant and the refraction seems suitably constant, 

 which fact the steadiness of the objects ob- 

 served had indicated in advance. This is 

 confirmed by the rigorous simultaneous meas- 



ures made by M. Maurain at Pambamarca and 

 by M. Gonnessiat at Panecillo. Under these 

 conditions it is possible to execute good 

 geodetic leveling. 



Latitudes of the Third Order. — The atten- 

 tion of the observers was called to the neces- 

 sity of obtaining observations for latitude as 

 often as practicable. 



The theodolite with micrometers could not be 

 used, and it was very difficult to transport the 

 meridian circle. After considerable progress 

 had been made the observers received acces- 

 sories which enabled them to use the theodo- 

 lite with micrometers in observations for 

 latitude. Captain Maurain observed a sec- 

 ondary latitude at Tacunga with the meridian 

 circle and then made observations for lati- 

 tude with the theodolite to ascertain the pre- 

 cision to be expected when that instrument 

 was used. The result was sufficiently good 

 to warrant its use for this purpose in the 

 mountains. There is always a systematic dif- 

 ference between observations on north stars 

 and those on south stars, but the errors from 

 many successive nights are always very small. 

 The observers will soon receive two Claude 

 Driencourt apparatus; this apparatus, which 

 has been described in the Astronomical Bul- 

 letin, Vol. XVII., gives results of great 

 precision and is very portable, and it can be 

 utilized at the geodetic stations which re- 

 main to be occupied, especially in localities 

 where gravity observations wiU be made. A 

 great number of observations for latitude of 

 the third order have been made with the 

 theodolite, one to the south of Eiobamba, one 

 near Eiobamba, two around Tacunga, three 

 around Quito (Pambamarca, Pichincha, 

 Corazon) and four around the northern base 

 line. 



Gravity. — This portion of the work has not 

 made much progress. The station at Eio- 

 bamba is reduced, but it still needs the ac- 

 curate determination of the rate of the side- 

 real clock. No other observations have been 

 made. It is still undecided what instru- 

 ments should be used at the secondary sta- 

 tions. The Sterneck pendulum does not ap- 

 pear to present as great advantages as it was 

 at first believed to possess. M. Maurain 



