ARTICLE XVII. 



Observations to determine the horizontal Magiietic Intensity and Dip at Louis- 

 ville, Kentucky, and at Cincinnati, Ohio. By John Locke, M. D., Professor 

 of Chemistry in the Medical College of Ohio. Read May 15, 1840. 



The following observations were made to determine the relative horizontal 

 magnetic intensities at Louisville, Kentucky, and Cincinnati, Ohio. The ap- 

 paratus used was that invented by Professor Bache, in which the needles are 

 made to oscillate in a rarefied medium. Two of the needles used (Nos. 1 and 

 2) were of the model of those of Professor Hansteen; the third (No. 3) was flat, 

 with lozenge points. 



Horizontal Intensity. 



Cincinnati, March 7, 1840. Latitude 39° 06' N.; Longitude 84° 27' W. 



No. of 

 Needle. 



No. 1 

 2 

 3 





Time of 



i 



Commencement. 



llh IQm 



05^ 



.6 



11 



47 



04 



.4 



12 



36 



05 



.6 



Mean Temp. 



56° 64' F. 

 58 00 

 60 00 



Duration of 

 500 Vibrations. 



25.6666 Min. 



25.3733 



20.6160 



Calculated duration 

 at 60°. 



25.6777 Min. 



25.3808 



20.6160 



Square of tlie 

 Time. 



659.34428 

 644.18500 

 425.01945 



Observations. 



Cloudy; sprinkles of rain, 

 do. do. do. 



do. do. do. 



Cincinnati, March 14, 1840. 



No. 1 

 2 

 3 



11'' 33™ 59^2 

 12 16 03.2 

 12 54 59.2 



48° 5' F. 

 45 

 45 5 



25.6600 Min. 



25.3600 



20.6066 



25.6954 Min. 



25.4151 



20.6239 



660.25358 

 645.92731 

 425.34525 



Beginning to rain. 

 Raining, 

 do. 



Louisville, Ky., March 10, 1840. Latitude 38° 03' N.; Longitude 85° 30' W. 



No. 1 

 2 

 3 



llh 44m 0.2^4 



59° 50' 



F. 



12 20 58.8 



57 50 





1 18 00.0 



57 10 





25.3333 Min. 



25.0200 



20.3333 



25.3363 Min. 



25.0290 



20.3368 



641.77777 

 626.45084 

 413.58540 



Clear; brisk N. W. wind, 

 do. do. do. 

 do. do. do. 



luouisville, March 11, 1840. 



No. 1 

 2 

 3 



111, 40m 04^8 



39° 



5'F. 



12 14 04 



41 







12 48 03.2 



43 





25.3000 Min. 



24.9733 



20.3200 



25.3622 Min. 



25.0421 



20.3400 



643.24119 



627.10677 

 413.71560 



Clear; wind moderate, 

 do. do. do. 

 do. do. do. 



VII. 3 Q 



