54 Proceedings of the Americmi Philosophical Society. 



"5th. That they are in their descending node when visible Aug. 10.5th, 

 and that their distance from the sun, in the ascending node, is not less 

 than 7 hundredths, and may be several times the earth's mean distance 

 from the sun. Hence, even if they are a continuous ellipse-formed stream, 

 it is only in one of these possible distances, viz. that of the earth from the 

 sun ; that this stream would be visible to a spectator on the earth, when 

 traversing its ascending node. If, near the sun, their aggregate might 

 appear as spots on the solar disc, or might intercept some of the solar 

 light and heat: if far beyond the earth, no traces of them would be found. 



" 6th. That the earth traverses this meteor-stream from the 5.5th to the 

 7.5th of February. The fact that no such stream has of late years been 

 noticed, shows that the first condition of No. 5, does not prevail. Mr. 

 Erman thinks that the diminution of the normal increase of temperature 

 at this date, as ascertained at several stations, for many years past, by Mr. 

 Madler, of Berlin, may possibly warrant the conclusion, that the second 

 condition takes place, and that the meteor-stream at this time is between 

 the earth and sun. That the first condition may have prevailed in 1206, 

 and the second in 1208, seems not improbable from history. This appa- 

 rent change in the appearance of the meteor-stream Mr. Erman ascribes 

 to the secular variations of its elements; the possibility of which is ad- 

 mitted by Olbers and Bessel. 



" 7th. That the greatest possible apparent motion of the common point 

 of convergence of their apparent paths, consistent with the existence and 

 observed position of this point, is one-tenth of a degree of a great circle 

 westward, in an hour." 



Mr. Walker remarked, that though much pains had been bestowed up- 

 on determining their apparent paths and duration, at the High School Ob- 

 servatory, he had as yet received no corresponding observations which 

 could throw light on the third conclusion of Mr. Erman. The motion of 

 the radiant — if any — according to Mr. Forshey's and his own observa- 

 tions, would seem to be in a south-easterly direction, of about one half of 

 a degree of a great circle per hour, a phenomenon not reconcilable with 

 the analysis of Mr. Erman. 



In conclusion, Mr. Walker referred, for the details of the Philadelphia 

 observations, to Mr. Forshey's paper read this evening. 



Dr. Hays communicated the particulars of a case of inability to distin- 

 guish certain colors, occurring in a man, a patient in Wills's Hospital, 

 under the care of Dr. Fox. 



This case, Dr. Hays remarked, presented the following points of in- 

 terest. 



1st. It confirmed the correctness of the observation made by Dr. Hays, 

 in a former communication, that no reliance can be placed on the account 

 of their own cases, given by those who labor under this defect; and that 



