On the Daily Motion of the Magnetic Needle. 145 



enable him to grind it " as fine as dust," yet I would submit, as 

 this metal completely fulfills every condition required by the 

 histoiy, and as dokimasy was then sufficiently advanced to allow 

 of such an alloy being- made, that it assumes a very high degree 

 of probability, being in complete and exact accordance both with 

 the sacred narrative and also with the ascertained state of the 

 metallurgic art at the time, that the golden calf was alloyed with 

 lead; that this brittle alloy, when stamped and ground as fine 

 as dust, was "strawed" on the water from the mount, of which 

 the Israelites drank, and that a solution of the idol was neither 

 effected nor even thought of. 



I am. Gentlemen, yoiu's, &e. 

 Putney, July 19. 1852. J. Denham Smith. 



XXI. Addenda to the Investigation on the Decennial Period in the 

 Magnitude of the Daily Motion of the Magnetic Needle. By 

 Dr. Lawont*. 



IN the June Number of this Magazine a paper from me will 

 be found, in which I have endeavoured to show that a de- 

 cennial period exists in the daily motion of declination ; at the 

 conclusion of the said paper it is hinted, that in the horizontal 

 intensity also a similar period probably exists. At that time the 

 observations of our magnetic observatory wei'e not so completely 

 calculated as to permit of a closer discussion of the subject. At 

 present, the calculations, at least so far as is necessary for a pre- 

 liminary investigation, are carried out, and I will not neglect 

 communicating the results. 



As magnitude of the daily motion of the horizontal intensity, 



I assume, approximately, the difference between the position at 



II o'clock in the morning and 6 o'clock in the evening, and 

 thereby obtain the following means for the years specified (ex- 

 pressed in ten-thousandths of the horizontal intensity) : — 



1843 7-8 



1844 6-9 



1845 6-6 



1846 11-4 



1847 12-1 



1848 14-3 



1849 12-0 



1850 10-7 



1851 9-1 



Although no regular transition, as in the case of the declina- 

 tion, is to be observed here, still the existence of a period is very 

 * From Poggenilorff's Annulen, vol. Ixxxvi. j) 88. 



Phil. Mug. S. 4. Vol. 4. No. 23. Aug. 1852. L 



