MARINE ALG OF BEAUFORT, N. C. 385 
It will be seen that the extreme range of temperature recorded is 28°, from 3 to 31°. 
The lowest temperature and the lowest average occur in February, while the highest 
temperature and the highest average occur in July. In the fourth column there is 
given the change of the average since the previous month. It will be observed that the 
greatest increase of the average occurs from March to April (5°), while that from April 
to May is only 0.1° less (4.9°). The greatest decrease of the average occurs from Sep- 
tember to October (5.6°), while that from October to November is nearly as great (5.3°). 
During the other eight months the average change is relatively small. 
It is interesting to compare with these figures the surface temperatures (expressed 
in degrees centigrade) recorded for Woods Hole, Mass., by Sumner, Osburn, Cole, and 
Davis (1913) and those given for Naples by Berthold (1882), since the former locality 
has a temperate algal flora, while the latter locality has a subtropical one. 
Woods Hole, Mass. Woods Hole, Mass. 
Naples, SITPRO SGT OID cada lt Naples; 
Maxi- | Mini- | Aver- Italy. Maxi- | Mini- | Aver- Italy. 
mum. | mum.| age. mum. | mum, | age. 
rd OF, 5G. °C: of CP 
bet Coa apotarmciy scence 23-6 17-22 | 20.97 25-27 
21-67 | 17.22] 19-55 } 
18.33 Io. 83 15-26 
12. 78 3-6 Sot teas 
8.6 — .28 Cm nwt tome artes 
At both of these places the highest temperature occurs in August and the lowest 
temperature in February. Woods Hole has a range of 25.55°, from —1.95 to 23.6°, 
while Naples has a range of 19°, from 8 to 27°. These figures indicate that Beaufort 
has a higher maximum and a lower minimum than Naples; but the record of Naples is 
less complete than that of Beaufort. 
LIGHT. 
While we have as yet no satisfactory measure of light, we can measure, in an approxi- 
mate way, the relative effect under different conditions of the rays of light which affect 
photographic paper. This has been done in the present instance by means of the 
Clements photometer. This instrument uses a strip of solio paper, successive portions 
of which are exposed at will through a small slot, the slot being opened or closed as 
desired by means of a sliding cover. Standards for comparison are obtained by exposing 
portions of the paper to direct sunlight for different measured intervals of time. Another 
portion of the paper is exposed for a definite time in the situation whose light is to 
be tested. By comparison it is then determined which of the standards is darkened to 
the same extent as the paper exposed in the test situation. From the relative time of 
exposure of the test paper and this standard it is thus possible to estimate the relative 
amount of light in the test situation compared with full sunlight. For example, if paper 
exposed in a certain situation for 10 seconds is darkened to the same extent as a standard 
exposed to full sunlight for 5 seconds, we estimate that the light in this situation is 50 
per cent as strong as full sunlight. It is, of course, necessary to make new standards 
for every series of tests, since the intensity of full sunlight will itself vary at different 
times and on different days. 
