172 



Sobescianum, Fein ^ernroljr aiiuimenbeu unb burd? 6palts 

 ö'ifnunaen ju beobachten, ^aüep wol)itte 1679, alö er 2)anji9 

 berud)te, biefen Q^eobadjtungeu, beren ©euaiügfeit er übrigen^ 

 überma^iö anrit()mte, M. ^oiimo^ 33b. III. ©. 60, 106 (9{nni. 

 2 unb 3), 154, 317 unb 355 O^lnm. 13.) 



" (@. 60.) ©puren ber täslid)en unb ilünblicben ^Seränber^ 

 lid)fett ber magnetifcfeen Olbmeidjung ijatten bereite in gonbou 

 .^eUibranb (1634) unb tu @iam ber «Pater ^adjarb (1682) erfannt. 



" (@. 61.) ^ergl. .^oömo^ 35b. I. ©.432—435 ^Uun. 29. 

 2)te vortrejflidje ^onftrucrion ber, nad) 95orba'i^ Eingabe juerfl: Don 

 genoir angefertigten Boussole d'Inclinaison, bie 9)?ü9lid)feit freier 

 unb langer ©cpiinngungeu ber ^tabel, bie fo fe()r i^ermiuberte 

 Oletbung ber Rapfen, unb hie rtd)ttge Qfufilelluug be^ mit gibelleu 

 t)erfel)enen 3n|l:rument^ l)aben bie genaue 9)ie(fung ber ^rbfraft 

 unter uerfcbiebenen ponen juerft möglieb gemad)t. 



*" (e. 63.) 3)ie ^a^^len, mit melcben tie folgenbe ^afel aii- 

 Oebt (j. 35. 1803—1806), beuten auf i^ie (5pod)e ber 33eobad)tnng; 

 bie in .klammern bem Xitel ber ©cbriften beigefügten Labien aUt 

 auf bu, oft febr üerfpätete 5Seröfent(icbung ber 35eobad?tungen. 



«» (@. 66.) ?)}ialu^ (1808) unb 3lrago'^ (1811) einfarbige unb 

 cbromatifcbe ^Pülarifation be^ 2icbte<5, f. .toämo^i 58b. IL ©. 370. 



'° (@. 67.) .So^mo^ 33b. I. ©. 186 unb 429 9lnm. 17. 



" (@. 68.) »Betöre the practice was adopted of delermiiiing 

 absolute values, the most generally used scale (and which still 

 continues to be very frequently referred to) was foiinded on 

 the time of Vibration observed bv Mr. de Humboldt about the 

 commenceraent of the present Century at a Station in the Andes of 

 South America, where the direction of the dipping-needle was 

 horizontal, a condition which was for some time erroneously 

 supposed to be an indication of the minimum of magnetic force 

 at the Earlh's surface. From a comparison of the times of 

 Vibration of Mr. de Ilumboldt's needle in South America and 

 in Paris, the ratio of the magnetic force at Paris to what was 

 supposed to be its minimum, was interred (1,3^8); and from the 

 results so obtained, combined with a similar comparison made 

 by myself between Paris and London in 1827 with several mag- 

 nels, the ratio of the force in London to thal of Mr. de Hum- 

 boldt's original siation in South America has been iuferred to 



