197 



Position geographique des principaux points de la Triangulation des 



Calif or nies et des cotes de V Ocean Pacifique du Mexique par Je 

 Comte Vincent Piccolomini. 



Volianos de las Virgenes 



Cap S. Lucas (Basse californie) • 



Monterrey (Haute californie) 



Guaymas (Departenient de Sonora) 



Matamoros (Texas) 



Id. Id. Barra grande de S. Yayo 



Id. Id. Barra del Rio 



Bejar (Texas) 



Mine d'or de S. Yago de los Caballeros 



Vulians de Tuxtla 



Namampateptl (Province de Vera Cruz) 



Bahia de San Francesco (au cap los Key ex dan; 



la haute Californie) 



Port de San Bias, totu: de I'eglise (guadalajara) 

 Volcanos de Colima 



29 91 14-35 

 23 08 35-27 

 36- 58 17-85 

 27 55 00-48 ;ill 



25 59 22-07 j 9 



26 30 27-15 

 25 53 03-11 

 29 74 88-93 

 25 13 77-04 

 IS 47 25-91 

 19 21 48-71 



37 59 17-29 

 21 67 05-54 

 19 03 45-17 



N.B. L'instmment employe pour determiner les Longitudes etait 

 un Chronometre de O. H. Bestor ; pour la mesure des triangles de 

 premier ordre je me servis d'un theodolite de dix pouces de diametre 

 sortant des ateliers de Munchi, pourvu de quatre verniers et don- 

 nant 10". Les elevations du sol furent determinees par des obser- 

 vations barometriques faites avec soin, souvent repetees et deduites 

 par le moyen d'observations correspondants ; eUes furent calculees 

 d'apres la methode d'Oltmanns et verifiees par celles du Baron Zach, 

 — Y.P. 



Report on the co-operation of the Russian and German ob- 

 servers, in a system of simultaneous INIagnetical Observations." By 

 the Rev. H. Lloyd, F.R.S., in a letter addressed to Sir John 

 F. W. Herschel, Bart., V.P.R.S. Communicated by Sir John Her- 

 schel. 



" On Magnetical Observations in Germany, Norway, and Russia." 

 By Major Sabine, R.A., V.P.R.S., in a letter to Baron von Hum- 

 boldt, For. Mem. R.S., dated Oct. 24th, 1839. 



These letters relate to communications which Professor Lloyd 

 and Major Sabine have had, conformably to a resolution of the 

 Council of the Royal Society, with the scientific authorities at Got- 

 tingen, Berlin, and St. Petersburg, respecting the organization of a 

 simultaneous system of magnetical observations. It appears, from 

 these letters, that the system proposed by the Royal Society is 

 viewed with general interest and approbation ; and nineteen stations 

 are enumerated at which there is reason to expect that magnetical 

 observatories, acting in concert, on that system, will be established. 



