IN NATURE dated May 4, p. 698, there appeared a review notice of the first three numbers of the Scientific Notes published by the Indian Meteorological Department. In criticising the first Note by Mr. Mohammad Ishaque on “A Comparison of Upper and Gradient Winds at Agra and Bangalore”, the reviewer took exception to Mr. Ishaque's statement that the gradient wind equation does not hold at the equator, and described the statement as “an unfortunate mistake”. Though Mr. Ishaque might with advantage have expressed himself a little more fully, it is profitable to recognise that there may be much truth behind his statement. For, it is not at all certain, as the reviewer would seem to imply, that motion in the free air over the equator under steady conditions is normally along isobars under the sole, effective control of the cyclostrophic component. On this very question Sir Napier Shaw (“Manual of Meteorology”, vol. 2, p. 266) has expressed the opinion that “we can no longer assume that the motion is along isobars for the equatorial region; it is controlled by some other con- sideration, and we do not know how far the new form of control may extend North and South of the equatorial belt”.