B. TERKESTRIAL PHYSICS AND METEOROLOGY. 81 



latter being wet and stormy. But in 1859, when he had ac- 

 cumulated far more accurate materials with reference to the 

 solar phenomena, he arrived at a result which he considered 

 more accurate than that deduced by him seven years earlier: 

 namely, that, in general, the years poor in sun-spots were 

 accompanied by only a very slight excess of temperature; 

 and, in view of all the circumstances, he decided that be- 

 tween the earth's temperature and the solar spots there ex- 

 isted either no connection at all, or one so slight that it could 

 not show itself in the mean yearly temperatures. During 

 the past two years, however, the important works of Mel- 

 drum, Koppen, and Celloria have appeared, and have seemed 

 to him to show that the subject is still worthy of attention. 

 "Wolf linds that the remarks of Koppen, to the effect that 

 there is a perfect parallelism between the changes in solar 

 spots and the changes in terrestrial temperature, may be true 

 at certain epochs, but at other times they present us with 

 most remarkable riddles; and he would incline to adhere to 

 his former conclusion that there is really no close connection 

 between temperature and sun-spots, did it not happen that 

 precisely in those years where the temperature ceases to fol- 

 low the solar spots, there also the curve of magnetic varia- 

 tions exhibits a remarkable discordance ; and that in respect 

 to the behavior of these three phenomena, in the years 1778 

 and 1789, we at present stand, as it were, before one of the 

 most remarkable enigmas in terrestrial physics, whose solu- 

 tion can but throw light upon this subject in all directions. 

 Passing to the consideration of the rain-fall, Wolf finds a 

 slight probability in favor of the law, announced by Meldrum, 

 that a periodicity actually exists in the rain-fall in tropical 

 regions similar to the solar-spot period. V* r olf s Astvon. Mitt., 

 No. 34, 134. 



METE0E0L0GY OF THE UNITED STATES* 



The annual report of the secretary of the Smithsonian Insti- 

 tution for 1872 reviews its general progress during the twen- 

 ty-rive years that have elapsed since he was called to its su- 

 perintendence. In speaking of the meteorological work that 

 has been carried out under him, after explaining the circum- 

 stances under which the Smithsonian has relinquished the 

 field of meteorology to the Army Signal-office, he explains 



D 2 



