Abstract
A new formula for the rate of evaporation of small water dróps was derived theoretically by M. Tsuji under the assumption that the surface of water is not saturated. When the radius of a water drop is very small the rate of evaporation derived from his formula is far slower than that derived from the known formula, for instance, of Ogiwara. It is interesting to decide experimentally whether M. Tsuji's theory is correct or not, because it is not only the problem of evaporation but also concerned with the formation and disappearance of cloud-and fog-drops. In the present investigation we measured under the microscopic field the rate of evaporation of water drops whose radii are smaller than 25 μ. The obt_??_ined results agreed with the theory of Tsuji approximately
