"Dr. Caswell’s predilection was for and astronomy. During the period of twenty-eight and a half years (from December, 1831, to May, 1860) he made, with few interruptions, a regular series of meteorological observations at the same spot on . These observations, precise as regards temperature and pressure, and including also much information on winds, clouds, moisture, rain, storms, the , &c, have been published in detail in Vol. XII of the "Smithsonian Contributions to Knowledge," and fill 179 quarto pages. Dr. Caswell continued his observations in meteorology with unabated zeal to the end of 1876, covering, in all, the long period of forty-five years."