The following is a statement of the results of certain acoustical investigations, in conducting which the late author was favoured by somewhat exceptional facilities. He writes: “ In a long series of endeavours, during balloon travel, to aid in the investigation of the physical constitution of the upper air, I have constantly sought to determine variations, however trivial or transient, in the currents through which the balloon has had to climb. Results have been alike curious and instructive. Thus, a globe of thistle down will not sport in the air as it does above the hedge rows, but will take an independent course, often at variance with that of the balloon, striking off widely in an apparently chance direction, or, more curiously, mounting upwards past the balloon, even though this may be also ascending from discharge of ballast.