IV INTRODUCTORY NOTE. 



what it is, no less than a due regard to the history of physi- 

 cal science in this country, and the interests of its present 

 votaries, require that these writings should now be collected 

 and made available : also that their publication and distri- 

 bution may be fittingly undertaken by the Smithsonian In- 

 stitution. Accordingly, at a meeting of the Regents, held 

 January 17, 1883, "Dr. Maclean having called the attention 

 of the Board to the fact that the sundry papers of Professor 

 Henry on scientific subjects had not been published in the 

 series issued by the Smithsonian Institution, it was Resolved, 

 That the Secretary be requested to have the scientific writ- 

 ings of Prof. Joseph Henry collected and published." At 

 the next stated meeting of the Board, held January 16, 

 1884, Dr. Asa Gray, Hon. W. L. Wilson, and Prof. S. F. Baird 

 were appointed a committee to supervise the publication of 

 Prof. Henry's writings. 



It was decided by them to include in this collection only 

 the published writings of Prof. Henry, and to arrange these 

 chronologically. A departure from this arrangement has 

 been made in transferring the series of papers detailing 

 Henry's extended observations on the phenomena of sound 

 from the position of their successive dates of publication 

 (1873 to 1877), and interpolating them between papers pub- 

 lished in 1855. This has been done for the purpose of equal- 

 izing the size of the two volumes. The second volume is 

 thus made to commence with the series of Meteorological 

 Essays, which, also published originally in successive years 

 (from 1855 to 1859), are here presented continuousl3^ These 

 Essays, although of a more popular character than the other 

 writings of the author, contain much original observation 

 and generalization, and therefore well deserve a place in this 

 collection. 



