AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 71 



seemed to crowd the firmament, while the milky way seemed to have desceaded 

 quite near the spectator. There he had seen the Zodiacal light, not only at the 

 horizon as before, but forming a complete arch across the sky, extending from the 

 eastern to the western horizon, and this, too, at every hour of the night. It was 

 sometimes so bright as to look like another milky way, stretching across the 

 heavens. He had brought back with him, he might state, some 115 plates ex- 

 hibiting this luminous arch, giving its boundaries as seen among the stars and 

 also the central line lengthwise. The brightness of the central portion was always 

 greatest, diminishing towards the edges. He would also state that he had made 

 drawings of the relative brightness of the various parts, and taken observations of 

 luminosity as compared with the Milky "Way. 



Mr. Jones made the following deductions from his observations : — 



First, That the substance giving out the Zodiacal Light formed a complete circle. 

 Several of his observations carried it round in a single night, so as to form a com- 

 plete circle, with the exception of a portion apparently near the sun. On the 26th 

 and 2'7th December for instance, he had taken five observations. The first of these 

 traced the light to within 16 degrees of the setting sun. the last to within 18 de- 

 grees of the rising sun ; thus forming a complete circle with the exception of 

 36 degrees. 



Secondly. It is a great circle in the heavens, forming an angle of 3 deg. 20 min. 

 with the ecliptic, the ascending node being at longitude 62 deg., and that descend- 

 ing at longitude 242 deg. As seeii from the earth, it has a width of about 28 deg. 



Thirdly. It is a geocentric circle ; for if it were heliocentric one portion would be 

 much nearer the earth than that opposite, and consequently appear of much less 

 breadth, which was not in accordance with the facts of the case. And again, if 

 heliocentric, the laws of the reflection of hght would require that the portions next 

 the sun should reflect less light than those near the zenith of the spectator, these 

 appearances were not visible. Again, that portion of the light near the horizon 

 showed an afiinity to the spectator's motions as he approached towards, or receded 

 from the ring. And this could only happen in case of a body not very far off. 



NOTICE OF THE LONGITUDE OF FEENANDINA, FLORIDA, BT CHRONOMETER EXCHANGES, 

 FROM SAVANNAH, GEORGIA. — BT A. D. BACHE, SUPERINTENDENT, AND CHARLES A. 

 SCHOTT, ASSISTANT, U. S. COAST SURVEY. 



(^Abstract for the Canadian Journal, communicated by the Author.) 



The longitude of Fernandina was required in order to know the direction of the 

 line across the peninsula of Florida to the Cedar Keys, which was in a general 

 way to be followed by the triangulation, to connect the Atlantic and Gulf Coast 

 work. Reconaissance had shown a triangulation to be practicable, connecting the 

 termini of the air line rail road. The longitude of Savannah had been obtained 

 by telegraph, and easy means existed for the transportation of chronometers be- 

 tween the two points. 



The paper contains an account of the operations, and incidentally a discussion 

 of personal equation, and of the performance of chronometers under different 

 circumstances. The final difference of longitude is given, which is of the greatest 

 importance, as the two best authorities differ some nine miles. The diagrams 

 urhich accompany it show the order of succession of the chroaometer trips, the 



