94 On the observations of Comets. 



ically, the flux, and reflux of the water ; but I was frequent- 

 ly at the lower end of Lake Superior, and found the water ei- 

 ther ebbing or flowing, except in violent gales, when it could 

 not be so well observed. 



Although I have stated only what came under my own 

 observation, still I feel great delicacy, in making the commu- 

 nication, for none of the inhabitants, had made similar ob- 

 servations. They had noticed a rise and fall in the water, 

 but only such as they attributed to the winds. It would seem 

 hardly possible that the lake should ebb and flow regularly, 

 and continually, and not have attracted the attention of some 

 of them, a few of whom have been there for many years. 



The periodical rise of the lower lakes, which takes place 

 in from three to seven years, may possibly, be the effect of 

 the height of water, in Lake Superior, and this caused by 

 an unusual depth of snow on its borders, and tributary 

 streams, or an uncommon rainy season. 



I never could observe, at the foot of the rapids of St. Marie, 

 any thing more than a light and sudden rise of water. The 

 rise of the water above never caused a corresponding rise 

 below. 



I know but little relative to the tides in Lakes Erie, Michi- 

 gan, Huron and Ontario, save vague rumor. In 1814, Lake 

 Ontario, was about two feet higher, than in 1813. My situa- 

 tion on that lake, during those years, enabled me to remark 

 this diflference. 



Art. XIII. — On the observations of Comets ^ by P. J. Ro- 

 driguez. 



Comets are the only bodies of the solar system, whose 

 elements are not known with that degree of exactness, which 

 the other parts of Astronomy have attained. This uncer- 

 tainty, owing principally to the want of correct observations, 

 will gradually diminish, as a greater number of observers 

 shall furnish proper data, to ascertain the orbits of those 

 bodies. It is true that the many able astronomers employed 

 in making celestial observations, leave no doubt of obtain- 

 ing those data if observations could be always made ; but 

 it sometimes happens that on account of the position of a 

 comet, or of the state of the atmosphere, no observations can 

 be made from the fixed astronomical observatories. Thus, 



