REPORT OF THE SECRETARY. 15 



the Auuual Eeports. The first consist of memoirs coutaining positive 

 additions to science resting on original research, and which are gener- 

 ally the resnlt of investigations to which the Institntion has in some 

 way rendered assistance. The Miscellaneons Collections are composed 

 of works intended to facilitate the study of branches of natural his- 

 tory, meteorology, etc., and are designed especially to induce individuals 

 to engage in studies as specialties. The Annual Eeports, beside an 

 account of the operations, expenditures, and condition of the Institu- 

 tion, contain translations from works not generally accessible to Amer- 

 ican students, reports of lectures, extracts from correspondence, &c. 



During the past year the seventeenth volume of the Contributions has 

 been distributed. It consists of a single memoir, by Lewis H. Morgan, 

 esq., of G02 quarto pages, illustrated by thirteen plates, in three parts: 

 First, a descriptive system of relationship of the Aryan, Semitic, and 

 Uralian families; second, the classiticatory sj'stem of the Ganowanian 

 family ; and third, a classiticatory system of the Turanian and Malayan 

 families. This volume has been distributed to institutions in this country 

 and abroad, and has met with approval as an important contribution to 

 the science of anthropology. 



The paper on "The rain-fall in the United States," referred to in the 

 last report, has been i)rinted, but it was found necessary to make 

 additions and corrections, especially in the charts, which have pre- 

 vented its distribution to the present time. 



A short paper by Professor William Ferrel, on "Converging series, ex- 

 pressing the ratio between the diameter and the circumference of a 

 circle," which was read before the National Academy of Sciences, has 

 been printed during the past year, and will form part of the eighteenth 

 volume of the Contributions. 



The papers of General J. G. Barnard, on " Problems of rotary motion 

 presented by the gyroscope, the precession of the equinoxes, and the 

 pendulum ;" of Mr. J. N. Stockwell, on " Secular variations in the orbits 

 of the eight principal planets ;" and of Dr. H. C. Wood, on " Fresh- 

 water algce," have been placed in the hands of the printers during the 

 past year, and will also form parts of the eighteenth volume of Contribu- 

 tions, to be issued in 1872. 



Another paper in course of publication is by Professor William Hark- 

 ness, of the United States jSTaval Observatory. It contains the records 

 and discussions of a series of magnetic observations by the professor dur- 

 ing thecruise of the Monitor Monadnock, from Philadelphia to San Fran- 

 cisco, in 18G5-'CG. The investigation was undertaken because the vessel 

 was heavily armored and the voyage extended far into both hemispheres, 

 thus afibrding a favorable opportunity of submitting Poisson's theory of 

 the deviations of compasses on iron ships to the test of rigorous observa- 

 tions, which had never been done before. The disturbing force acting on 

 a compass-needle is expressed as a function of the force of terrestrial mag- 

 netism, and of certain constants ])eculiar to the ship upon which the 



