Aincrlcan Association. 24-5 



towards each otlier. This showed that it was the same object 

 seen from ditierent positions, North or South of the ecliptic, 

 and having its loccality within the tropics. The Zodiacal light was 

 not seen till the twilight ceased, but that gave only an indefinite 

 idea of the time when it became visible at difterent places, because 

 in the tropics there was little twilight. In northern latitudes the 

 light had a greater altitude ; but owing to the long twilights, was 

 little visible, though it might be observed in the vernal and au- 

 tumnal equinoxes even in this latitude. The light in the morn- 

 ing was not of the same colour as in the evening ; in the first case 

 being greyish, in the other having a reddish hue, depending ovi 

 the approach or heat of the sun. After sunrise, he had seen it 

 reach the zenith, with a breadth of only 2| degrees. Sometimes 

 the phenomenon was very beautiful, as if a gauze veil were spread 

 over the atmosphere, through which the stars could be readil}^, 

 though dimly seen. Thus the light stood alone and distinct from 

 all others, its central line being parallel to the ecliptic, a little to 

 the north or south of it, but sometimes corresponding with it. 

 His idea of the origin of the light, from all these facts, was that it 

 was the elfect of the illumination of that portion of the earth's at- 

 mosphere on which the sun's rays fell in a perpendicular direction. 

 To illustrate this, let it be remembered that if the sun's rays were 

 admitted perpendicularly through a hole in the shutter, and allre- 

 liected light cut olF, the atmosphere, or the particles floating in it, 

 become plainlj- visible as well-defined objects." 



On a subsequent day the same subject was brought forward by 

 the llev. M. Jones, U. S. N., who on the basis of a series of ob- 

 servations made by himself at Quito, maintained the conclusion 

 that the Zodiacal light is a circle of nebulous matter not helio- 

 centric, as heretofore supposed, but geocentric ; in short if we 

 understand the view correctly, that this mysterious appearance is 

 an attendant on our planet, related to it as the well known rings 

 are to Saturn. We arc not in a position so to investigate the 

 facts presented, as to accept either of these theories as final, but 

 it is evident that Commodore Wilkes and Mr. Jones have collect- 

 ed facts that will bring us nearer to settled conclusions on the 

 subject. 



Passing over seveial papers of a more jjurely physical character, 

 we reach a singular and elaborate series of papers by Mr. Gibbons, 

 of the U. S. mint, on the 



WEIGHTS AND MKASUKES OK VAIUOUS CUUM"KiKS. 



Tlieso papsrs presented in a condensed form many curious 



