172 



Sübe sei an um, fein 5ernrcl)r aivuiw^nben unb burc^ ©palt= 

 öjfmtnoien ju beobacbten. S^aüev woljnte 1679, a\6 er ©anjig 

 befucfcte, biefett iBeoba^tungeii, bereu ©enauigfeit er «brigeu^ 

 übermä^iä aurül)mte, bei. ÄoömoeS 23b. III. @. 60, 106 (Otnm. 

 2 unb 3), 154, 317 iinb 355 02Inm. 13.) 



"" (®. 60.) ©puren ber täglichen unb ftünbttct)en 23eränber: 

 lici)feit ber maanetifc^en Qtbiveicbung l)arren bereite tu 2onboii 

 .^ellibranb (1634) unb in @iam ber ^ater 2;ad}arb (1682) erfannt. 



" (®. 61.) aSergl. .toömoö »b. I. @. 432— 435 mm. 29. 

 £)ie »ortreflic^e Sonjliruction ber, md) 93orba'»< Eingabe juerft öon 

 genoir angefertigten Boussole d'Inclinaison , bie ?i)?ögU(t)feit freier 

 unb langer ©cbtvingungen ber 9?abel, bie fo fefjr uerminbertc 

 Oieibung ber Bap^m, unb bie ricbttge 9(uf(T:eüung be^ mit 2ibellen 

 »erfe^enen S'ifiJ^i'i^fiit^ ^aben bie genaue 9)?eflrung ber (Erbfraft 

 unter verfd)iebenen ^'^''e» Jiifrfl möglicb 8emact)t. 



*' (@. 63.) Sie 3ai)len, mit roelcf)en bie folgenbe ^afel an: 

 ^ebt (j. 93. 1803—1806), beuten auf bie epodje ber SSeobacbtung; 

 bie in .Klammern bem $;itel ber ©d^riften beigefügten ^a^len aber 

 ttuf bie, oft fe^r »erfpatete ^ijeröjfentlic^ung ber 58eobacbtungen. 



" (©■ 66.) gjialuö (1808) unb SIrago'ö (1811) einfarbige unb 

 c^romatifdbe ^))olarifation be6 2icf>te^, f. ÄO'imo^ 58b. II. ©. 370. 



""> (@. 67.) Äoömo^ 58b. I. ©. 186 unb 429 3(nm. 17. 



^' (@. 68.) »Betöre the practice was adopted ofdelermining 

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

 continues to be very tVequently referred lo) was founded on 

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

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

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

 horizontal, a condition which was for some time erroneously 

 supposed to be an indication of Ihe minimum of magnetic force 

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

 Vibration of Mr. de Humboldl'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 inferred (l,3i8); and from the 

 results so oblained, combined with a sirailar comparison made 

 by myself bclween Paris and London in 1827 with sevcrai mag- 

 ncls, the ratio of the force in London lo ihat of Mr. de Hum- 

 boldt's original Station in South America has been inferred to 



