' OVER A WIDE EXPANSE. 99 



perature of the American continent and adjacent islands, have been 

 completed to the close -of the year 1870, and extensive tables 

 representing the daily extremes, or the maximum and the minimum 

 at the regular observing hours, have been prepared. 



" An exhaustive discussion of all the observations available for the 

 investigation of the daily fluctuations of the temperature has been 

 made, and this part of the work is now ready for the printer. 



" The discussion of the annual fluctuations of the temperature has 

 been commenced and carried as far as the present state of other parts 

 of the discussion would permit. 



" The construction of a consolidated table giving the mean results, 

 from a series of years, for each month, season, and the year, at all 

 of the stations, which will probably exceed 2,500 in number, has been 

 begun and completed for that part of the continent lying north of the 

 United States, and also for several of the States. This is perhaps the 

 most laborious, as it is one of the most important parts of the dis- 

 cussion. In many of the large cities there are numerous series, made 

 by various observers, at different hours, all of which have to be 

 brought together, corrected for daily variation, and combined to 

 obtain the final mean. To give some adequate idea of the time and 

 labour involved in the preparation of these tables, it may be 

 mentioned that, in the State of New York alone, there are about 

 three hundred series, which are derived from nearly two million 

 individual observations. 



" The principal sources from which the general collection of 

 results has been derived, may be enumerated as follows : — 



" 1. The registers of the Smithsonian Institution, embracing 

 upward of three hundred large folio volumes. 



" 2. The publications of the Institution, Patent-Office, Department 

 of Agriculture, and public documents. 



" 3. All the published and unpublished records of the United 

 States Army, United States Lake Survey, and United States Coast 

 Survey. 



" 4. The large volume compiled by Dr Hough, from the observa- 

 tions made in connection with the New York University System, 

 the records made in connection with the Franklin Institute, and 

 those obtained from numerous observatories and other scientific 

 institutions. 



" 5. The immense collection of printed slips, pamphlets, manu- 

 scripts, &o., in the possession of the Smithsonian Institution. 



" The work has been somewhat retarded by the colleotiou aud 



