219 
the sun’s altitude diminishes. This Linsser shows in the following 
table.“ 
| Maximum dura- | Altitude of sun at) Relative Gunntity of heat 1 re- 
| tion of Se: | noon. ceived by the ground in 1 
[gases ‘a =| day under an atmosphere 
Date. | Menion Ne St. Pe- | Se pape. whose tr AUIpATENCY, is 0. ie 
Gat. 45.40/*8burg | gat, 45.4¢ tersbuire 
N_). (lat. 60° Ne (lat. 60° Tht Lat. | Lat. | Lat. 
N.). N.). | 40° N. | 50° N.| 60° N. | 70° N. 
Hours. | Hours. | De grees. | Degrees. | 
January 16 .-....----------- 9.0 | Geshe) 2325 9.0| 150 vO es wats 0 
February 15._..-...---.---- 10.3 | 9.2] 381.5 16.9} 210 155 65 14 
I Prct (ee 1.9; ws] 42:8] - 282] 400) 205] 190 95 
aprile ye tenet Sait B.5| 14.5} 543) 38.7) 520) 450 | 360 255 
Winn 7 dL = oe ee 14.8 | ibrar 63.6 | 49.1) 615 570 | 505 | 425 
ume tl yee. es. 15.6 | 18.8 67.8 | 53.4 | 650 625 | 570 | 505 
rity Gee es! See 15.3 18.1 66.0 51.5} 630 585 | 525 450 
PANT OUIStIO) sae s a 14.1 | 15.6 | 58.4 | 43.9 5a0 | 480 395 295 
Sentomberilst=asse ns s- 12.6 | 13.0 | 447 33.2] 430] 385 230 125 
Octoborloeuse ses ue | 10.9 10.2 | 35.8 Pla 280 | 185 | 90 | 25 
November 15__.___.._-. Lee 9.5 7.6 26.2 | VEC 85 20 0 
Wecemiberi6 2-.222-2- =. --..- 8.7 | 6.0 21.3 | 6.7 135 | a) 2 0 
In reference to the first part of this table Linsser remarks that 
the intensity of the light of the sun varies as the sine of the angular 
altitude of the sun, so that from the maximum altitude on any day 
we get an approximate idea of the influence of sunshine; and we see 
also that the farther north we go the longer duration of the sunshine 
is partly counterbalanced by the diminishing intensity of its 
influence.? 
Linsser remarks that the theory of compensation between duration 
of the day and intensity of sunshine may also be tested by considering 
the effect of ascending a mountain, where there is no increase of dura- 
tion but a great increase in the intensity, of sunshine. If the rapid 
development of the plants on the mountains is due to the increase in 
the intensity of the light, then how can the diminution of intensity 
in northern regions bring about the rapid development that is demon- 
strated in the experiments of Von Baer and Schuebeler and Ruprecht 
which are quoted and analyzed in the following paragraphs? 
@To which I have added three columns of “aaiee fae of the total heat 
received in twenty-four hours on each date, as interpolated from Angot’s tables, 
for a coefficient of transparency equal to 0.70.—C. 4 
b The exact figures that give the relative sum total of the direct sunshine 
and the diffuse daylight for various latitudes and solar altitudes for clear and 
cloudless days have been published by Marie Davy, Angot, Wiener, and others. 
The figures that I have given in the last part of the above tables from Angot 
show still more clearly to what extent the effect vf sunshine diminishes as we 
approach the pole, but how surprisingly powerful are the consecutive twenty- 
four hours of sunshine on June 15 within the Arctic Circle.—C, / 
