142 BULLETIN OF THE 



The second communication was by Mr. William McMuutrie, 



ON THE METEOROLOGICAL CONDITIONS AFFECTING THE CULTURE 

 OF THE SUGAR BEET. 



Mr. McMurtrte's paper is to be published in full in the annual 

 report for 1879 of the Commissioner of Agriculture. 



184th Meeting. June 19th, 1880. 



The President in the Chair. 



Twenty-six members present. 



The President announced to the Society the election as members 

 of Messrs. C. H. Davis, Z. L. White, A. W. Greely, C. E. Kil- 

 BouRNE and J. P. Story. 



The first communication for the evening was by Mr. D. P. Todd 



ON A MECHANICAL ATTACHMENT FOR EQUATORIAL MOUNTINGS 

 to FACILITATE SWEEPING IN RIGHT ASCENSION. 



The arc of the sector which drives the polar axis is graduated 

 in hours and parts thereof. Sliding upon this graduation are two 

 vernier-like pieces, each of which carries a projecting metallic 

 point. By clamp-screws the verniers may be attached to any 

 part of the sector-arc. A revolving collar, with a screw for clamp- 

 ing, surrounds the polar axis adjacent to the sector, and carries a 

 projecting arm the end of which will just touch both the metallic 

 points attached to the verniers. An electric apparatus is so dis- 

 posed that whenever the projecting arm comes in contact with 

 either point on the verniers, a telegraphic sounder shall beat, or an 

 electric bell shall ring. In using the device, the two verniers are 

 set, by means of the sector-graduation, at a distance apart equal to 

 the length of the zones to be searched. The sector is undamped 

 from the polar axis, and connected with the clock, and the latter 

 set in motion. The telescope is then set upon one end of the zones^ 

 and the projecting arm brought in contact with the corresponding 

 vernier-point. The collar is clamped to the polar axis in that 

 position, and the telescope set in declination. As the instrument is 

 moved back and forth in right ascension, the electric signal will 

 apprise the ear of the observer whenever the telescope reaches 

 either limit of the zones. 



