DISCUSSION OF THE VERTICAL FORCE. 



Table II. 



— Record of the Monthly Means of the 



Vertical Force Magnetometer Readings 



FOB jEACH Observing Hour, and reduced to 



UNIFORM Temperature of 66° Fah. 



1841. 



0" 



2 



4 



6 



8 



10 



Noon. 



14 



16 



18 



20 



22"' 



+17» 



February- 



861 



861 



860 



857 



851 



846 



845 



849 



847 



878 



872 



867 





March 



956 



954 



949 



943 



936 



933 



931 



928 



941 



953 



957 



957 





April 



1004 



997 



994 



988 



982 



982 



981 



982 



989 



997 



1006 



1009 





May 



1033 



1031 



1030 



1021 



1012 



1009 



1008 



1008 



1012 



1022 



1037 



1043 





June 



641 



634 



631 



621 



618 



618 



616 



620 



627 



641 



652 



653 



July 



704 



698 



686 



675 



669 



666 



667 



700 



684 



695 



708 



707 





Aueust 



684 



680 



673 



665 



664 



655 



653 



659 



663 



672 



686 



690 





September 



665 



660 



657 



651 



642 



633 



632 



632 



637 



646 



656 



662 





October 



583 



582 



578 



572 



562 



559 



561 



561 



569 



577 



581 



582 





November 



540 



543 



540 



544 



531 



528 



526 



527 



532 



535 



538 



540 





December 



602 



595 



595 



599 



593 



598 



605 



600 



606 



613 



613 



613 





Notes to the above table: — February 25tla, 6'' 17"", temperature interpolated, 28°. March 2d, 0'' 17", 

 reading 32 minutes late, i=46°.8. March 11th, 22" IT"", reading 49" late, <=41°.7. March 27th, 

 20'" 17", reading 40" late, i!=64°.8. March 29th, 22'' 17", reading 43" late, i!=50°.5. April 9th, 

 le"" 17", reading 25" late, r=920, i;=57°.6. April 30th, 0'' 17", reading 59" late, »-=805, i!=490.3. 

 May 22d, li^ 17", observations discontinued. Between this date and June 1st the instrument was 

 readjusted, the corrections required to make the readings of the first four months comparable with the 

 continuous series following will be investigated further on. June 29th, 22'' 17", reading 38" late, 

 temperature 81°. 8, interpolated. July 22d, 16'' 17"", temperature 84°. 5 interpolated. August 23d, 

 24th, seven observations were omitted between 20'' 17" and 8'' 17" on account of the magnet being 

 fixed by a spider's line which was found attached to the mirror. August 24th, 14'' 17"', observation 

 rejected, the sun shining on the box. October 4th, 16'' 17", sun shining on the needle ; October 13th, 

 22'' 17", observation 7" late ; October 28th, 22'' 17™, observation 67" late. In December the variations 

 of temperature are unusually large ; they seem to demand a greater value of the temperature coefficient. 

 December 8th, le*" 17"", observation 8" late; December 20th, 4'' 17°', observation 9" late; December 

 30th, 18'' 17", temperature 69o.0, interpolated. 





Table II 



— Continued. 



Vertical Force Readings at 



66° Fah. 





1842. 



0" 



2 



4 



6 



8 



10 



Noon. 



14 



16 



18 



20 



22'' 



+17i'» 



January 



651 



651 



663 



659 



657 



651 



661 



648 



660 



679 



674 



674 





February 



705 



704 



714 



714 



707 



698 



704 



696 



699 



714 



707 



701 





March 



661 



656 



662 



664 



663 



662 



655 



649 



655 



667 



673 



666 





April 



666 



655 



659 



655 



653 



654 



649 



643 



645 



655 



667 



670 





May 



662 



665 



657 



649 



646 



647 



652 



644 



647 



654 



664 



665 





June 



674 



669 



663 



658 



648 



643 



639 



640 



636 



652 



665 



663 





July 



690 



685 



675 



667 



663 



656 



652 



651 



656 



669 



681 



684 





August 



689 



687 



685 



682 



675 



668 



655 



655 



665 



677 



684 



686 





September 



698 



692 



696 



689 



686 



677 



671 



671 



673 



679 



690 



698 





October 



707 



699 



703 



712 



696 



709 



708 



707 



707 



709 



711 



706 





November 



718 



710 



723 



725 



713 



715 



713 



713 



716 



711 



718 



718 





December 



708 



708 



714 



709 



716 



711 



709 



707 



705 



710 



713 



713 





Notes to above table: — February 3d, 14'' 1*7^", the temperature 73°. 5 is interpolated. May 9th, 

 lO"" 17i", the temperature 59°.6 is interpolated. June 6th, 0'' 17^", 2'' 17i", and 18'' 17^", the tem- 

 peratures 70°. 4, 71°.0, and 74°. 4 respectively, were interpolated. August 3d, 12'' 17-|-"; 5th, 

 22" 17i"; 6th, 10" lYi", and 31st, 14" 17i", the temperatures 69°.0, 73°.7, T6°.0, and 6'7°.6 

 respectively, were interpolated. September 1st, 22" IT^", the temperature 7*7°. is interpolated. 

 October 8th, 2" 17^"; 21st, 10" 17^", and 28th, 6" 17^", the temperatures 66°.!, 68°. 1, and 70°. 8 

 respectively, were interpolated. November 3d, 14"17i"; and 16th, 6" IH" the observations are 

 6" and 7" late. 



