Dr Richardson has reduced more carefully the Observations published in the Appendix to Franklin's Second Journey on the Force of Solar Radiation. From observations on a thermometer in the shade compared with those on a thermometer with blackened bulb in the sun, he finds a tolerably regular daily curve of radiation having its maximum at noon. But when (after allowing as far as possible for the disturbing influence of the wind) different months are compared, it is found that in spring the radiation is more intense than in summer after the disappearance of the snow, which Dr Richardson is disposed to attribute to a greater purity in the air at the former period.