II. Proceedings of the council of the Royal Society with reference to the undertaking of certain physical observations in India

On the 13th of February 1866, J. S. N. Hennessey, Esq., First Assistant on the Trigonometrical Survey of India, addressed a letter to the President, in which, after explaining the nature of the calls upon his time occasioned by his professional duties, he offered to devote any portion of his leisure to such scientific experiments as the President might direct. He stated that he was resident at Mussoorie from May to October, residing at Dehra during the remainder of the year, from which place, however, he would be able to visit Mussoorie occasionally, such as once a week. Mussoorie is a hill-station or town, at an altitude above the sea-level of about 6700 feet, in lat. 30° 28' N., and long. 78° 10' E. With reference to the climate of this place he observes, “In September the skies begin to clear, and from September 15 to about December 15 there prevails at Mussoorie a clearness of atmosphere such as I have never known in my wanderings. I mention this period in particular; but at all times, when the sky is clear of clouds, the intensity of the heavenly bodies is something exquisite. I have seen Venus distinctly at midday with my unaided eye. It is this wonderful transparency of atmosphere to which I would draw particular attention.” This letter was read to the Council on the 28th of June, and was ordered to be printed, and the President was requested to communicate it to such men of science as he might see fit, with the view of obtaining suggestions with reference thereto.