532 



SCIENCE. 



CORRESPONDENCE. 



71? the itditor of " SCIENCE." 



It seems to me that Pres. Gaines' objection to the 

 accepted theory of vision (see Science of Aug. 6, p. 370) 

 may easily be answered. 



It is universally agreed that vision is a sensation pro- 

 duced by ethereal undulations, and that these undulations 

 are induced by molecular motion in a luminous body. 

 Each point of a luminous body is a radiant point, that 

 is, emits rays of light in every direction, and it is by 

 some of these rays of ethereal undulations, either directly 

 from the luminous point or refracted by, or reflected 

 from, some non-luminous body, that all impressions of 

 vision are made. Hence, all non-luminous objects are 

 manifested to vision by reflected light, but reflected light 

 is also radiant light ; that is, reflected ethereal waves 

 radiate from every point of non-luminous objects mani- 

 fested to vision. These waves have fallen upon the 

 reflecting surface (not necessarily a minimum surface or 

 front) from various directions, many of them reflected 

 from other non-luminous objects, and, the angle of re- 

 flexion being the same as the angle of incidence, they 

 necessarily radiate from the object ; and by their differ- 

 ence of intensity, that is, by the different capacities of 

 contiguous surfaces to reflect rays in a particular direc- 

 tion, we receive different impressions from the different 

 parts of the object, and hence assign to the object pecu- 

 liarities corresponding to the peculiarities of the sensa- 

 tions produced. Hence, though I admit that we become 

 cognizant of objects by radiant light, I contend that in 

 all cases where the object is not self-luminous, the rays 



that impress us are reflected rays produced by some 

 luminous body of which we learn nothing from these 

 reflected rays. J. E. Hendricks. 



Des Moines. 



ANOTHER CONFIRMATION OF PREDICTION. 



By Pliny Earle Chase, LL.D. 



On the 4th of October, 1878, I presented a communi- 

 cation to the American Philosophical Society,* in which 

 I showed that the position of Watson's first intra-Mer- 

 curial planet, as computed by Gaillot and Monchez, 

 represented the third intra-Mercurial term of my har- 

 monic series. At the last meeting of the British Asso- 

 ciation, Professor Balfour Stewart read a paper in which 

 he gave indications of sun spot disturbances by a planet, 

 revolving in 24.011 days, and consequently having a 

 semi-axis major of .163. This confirmation, both of my 

 own prediction, t and of the calculations of. the French 

 astronomers, is the more interesting, because the first 

 confirmation of my series was contained in a communi- 

 cation which was made to the Royal Society by Messrs. 

 De la Rue, Stewart and Loewy, forty-one days after I 

 had announced the series to the Philosophical Society, 

 and published it in the New York Tribune.}; The 

 accordances are as follows : 



CONFIRMATION. 

 267. De la Rue, S. & L. .267 

 g j Gaillot & Monchez .164 

 ' / Stewart - - .163 



PREDICTION. 

 1st interior harmonic term 



3d 



*Proc. A. P. S., xviii., 34-6. 

 tlb., xiii., 238. 

 Jib., p. 470. 



METEOROLOGICAL REPORT FOR NEW YORK CITY FOR THE WEEK ENDING OCT. 29, 1881. 



Latitude 40 45' 58" N.; Longitude 73 57' 58" W.; height of instruments above the ground, 53 feet ; above the sea, 97 



feet ; by self-recording instruments. 



BAROMETER. 



THERMOMETERS. 





MEAN FOR 

 THE DAY. 



MAXIMUM. 



MINIMUM. 



MEAN. 



MAXIMUM. 



MINIMUM. 



maxi'm 



OCTOBER. 



Reduced 

 to 



Freezing. 



Reduced 

 to 



Freezing. 



Time. 



Reduced 

 to 



Freezing. 



Time. 



Dry 

 Bulb. 



Wet 

 Bulb. 



Dry 

 Bulb. 



Time. 



Wet 

 Bulb. 



Time. 



Dry 

 Bulb. 



Time. 



Wet 

 Bulb. 



Time. 



In Sun. 



Sunday, 23.. 

 Monday, 24.. 

 Tuesday, 25.. 

 Wednesday, 26. - 

 Thursday, 27.. 

 Fiiday, 28.- 

 Saturday, 29.. 



29.989 

 29.640 

 29.415 

 29.810 

 30.015 

 30.113 

 30.020 



30.104 

 29.848 

 29.50S 

 29.982 

 30.058 

 30136 

 30.112 



a. m. 

 a. m. 

 a. m. 

 12 p. m. 

 9 a. m. 

 9 a. m. 

 a. m. 



29.848 

 29.508 

 29-338 

 29.500 

 29.982 

 30.012 

 29.910 



12 p. m. 

 12 p. m. 



2 p. m. 



a. m. 



a. m. 



a. m. 

 12 p. m. 



60.6 

 57-3 

 57-° 

 45-3 

 48.6 



5'-7 



59-3 



56- 3 

 56.6 



54° 

 40.7 

 43.0 

 45-3 



57- 3 



69 

 61 

 64 

 55 

 59 

 56 

 62 



4 p. m. 

 a. m. 

 4 P- m, 

 a. m. 

 4 p. m. 

 2 p. m. 

 12 p. m. 



60 

 58 

 60 

 50 

 49 

 48 

 61 



4 p. m. 



a. m. 

 4 p. m. 

 a. m. 

 4 P- m- 

 2 p. m. 

 T2 p. m. 



51 

 54 



52 



38 

 34 

 44 

 54 



7 a. m. 

 12 p. m. 



5 a. m. 

 12 p. in. 



6 a. m. 

 6 a. m. 

 a. m. 



Si 

 54 



52 



37 

 34 

 41 

 48 



7 a. m. 

 12 p. m. 



5 a. m. 

 12 p. m. 



6 a. m. 



8 a. m. 

 a. m. 



»25- 



69. 



108. 



110. 



109. 

 94- 

 64. 



Mean for the week 29 857 inches. 



Maximum for the week at 9 a. m., Oct. 28th 30.136 " 



Minimum 11 at 2 p. m., Uct. 25th 29.338 * l 



Range 798 



Dry. Wet. 



Mean for the week. 54.2 degrees 50.4 degrees 



Maximum for the week, at 4 pm. 23d 69. " at 4 pm 23d, 60. " 

 Minimum " 6 am. 27th 34. at 6 am 27th, 34. 



Range " " 35- " " 



WIND. 



HYGROMETER. 





CLOUDS. 















VELOCITY 



FORCE IN 









RELATIVE 





CLEAR, 













DIRECTION. 



IN MILKS. 



LBS. PER 



FORCE OF VAPOR. 



HUMIDITY. 





OVERCAST. 



JO 















SQR. FEET. 

























OCTOBER. 









Distance 



M 





S 



6 



e 



E 



E 



E 





B 



6 





B 







7 a. m. 



2 p. m. 



9 p. m. 



for the 



« 



Time. 



a 



d 



d 



« 



d 



d 





« 



d 





d 











Day. 



S3 













H 









w 







Sunday, 



23. 



w.s. w. 



s. w. 



s. w. 



225 



3/2 



3 pm 



•374 



.380 



•447 



100 



55 



77 









2 CU. 



XO 





Monday, 



24- 



w. 



n. e. 



e. 



124 



% 



10 pm 



.482 



•43° 



•43° 



100 



93 



93 



10 





10 



10 



\ 



Tuesday, 



25- 



e. 



w. s. w. 



w. n.w. 



116 





7.15pm 



.388 



•443 



•3°9 



100 



82 



64 



10 





7 CU. 









Wednesday ,26. 



n. w. 



n. w. 



n. 



338 



954 



10.15 am 



.228 



.162 



.190 



76 



45 



74 



















Thursday, 



27. 



w. n.w. 



w. 



w. s. w. 



.63 





4 pm 



.204 



.191 



.231 



100 



41 



55 



















Friday, 



28. 



n. e. 



n. e. 



e. 



93 



ig 

 7% 



0. 10 pm 



.192 



.230 



•244 



61 



5« 



60 



4 cir. cu. 







1° 





Saturday, 





e. 



s. s. e. 



s. s. e. 



220 



12 in 



•321 



•5°5 



■523 



74 



94 



94 



10 





10 



[O 





RAIN AND SNOW 



DEPTH OF RAIN AND SNOW 

 IN INCHES. 



Time 

 of 



4.50 am 

 10 pm 



3.15 am 



Time 



of 

 End- 

 ing. 



2 pm 

 11 pm 



12 pm 



Dura- 

 tion, 

 h. m. 



9.10 

 x .00 



20.45 



< o 



•37 



Distance traveled during the week '1279 miles. 



Maximum force gj£ lbs. 



Total amount of water for the week 



Duration of rain 



DANIEL DRAPER, 

 Director Meteorological Observatory of the Department 



57 >nch. 



1 day, 6 hours, 55 minutes. 



Ph. D. 



of Public Parks, New York. 



