248 Scientific Intelligence. 



1904 few measures of the ' solar constant' worthy to be compared 

 with the series of 1903 have been obtained, but taking the best of 

 the measures it appears that high values of solar radiation in 

 February, 1904, and lower ones in the subsequent months are 

 indicated, as shown in Table II, given below. This appears to be 

 in general accord with the mean temperature observed over the 

 North Temperate Zone, except that it seems probable that the 

 solar radiation was high in January as well as February, but the 

 lack of good observing weather prevented our recognition of it." 



The importance of this subject is remarked upon in its bearing 

 upon forecasts of temperature, in case further research serves to 

 confirm the indications now obtained as to a general parallelism 

 between measures of solar radiation and terrestrial temperature. 

 For this work, however, a better station for observation than 

 Washington is needed. 



15. Terrestrial Magnetisyn. Results of Magnetic Observations 

 made by the Coast and Geodetic Survey between July 1, 1903, 

 and June SO, 190Jf ; by L. A. Bauer. Appendix No. 3, Report 

 for 1904. Washington, 1904. — This report* contains the usual 

 detailed statement of magnetic observations made in the United 

 States and outlying territories during the year ending June 30, 

 1904 ; an interesting feature is the introduction of observations 

 made at sea by the Survey vessels, this is a new departure begun 

 in February, 1903. In the introductory summary of results 

 reached some interesting notes are made, particularly in regard to 

 the changes of magnetic declination in Louisiana, We quote 

 some paragraphs : 



"The results of this detailed work in Louisiana have been 

 extremely interesting. First, it has been clearly demonstrated 

 that there was a reversal in the expected course of the secular 

 variation which took place about 1898. Past observations made 

 in the vicinity of New Orleans show that the magnetic declina- 

 tion, which is east, reached a maximum amount of about 8f ° 

 near the year 1830. It then began to diminish, and, in accord- 

 ance with the laws of the secular variation pertaining north and 

 east of the agonic line, i. e., in the Atlantic States, where west 

 declination is known to be increasing at present on the average 

 about three minutes per year, a turning point was under ordinary 

 conditions not to be expected before some time about the middle 

 of the present century. Instead, however, it was reached about 

 1898, so that east declination reached a minimum value of 5^° in 

 about seven decades after a maximum value — the shortest inter- 

 val between a maximum and a minimum value thus far revealed 

 anywhere on the earth. East declination is now increasing in 

 Louisiana at the rate of about one and one-half to two minutes 

 per annum. The total change between maximum and minimum 

 at New Orleans, as above stated, was about 3^°. 



The early reversal produced a larger annual change between 

 the years 1860 and 18*70 — about six minutes — than has generally 

 been experienced in the United States, although elsewhere, as, for 



* See also p. 261. 



