The two chief remaining instruments are those for measuring the amount of rainfall and of full sunshine. The rain gauge consists essentially of a funnel to collect the rain, and a graduated glass to measure it. The sunshine recorder usually consists of a large glass globe arranged to throw an image of the sun on a piece of specially prepared paper. This image, as the sun moves in the sky, moves along the paper, charring it as it moves, and at the end of the day it is easy to see, from the broken, burnt trace, at what hours the sun was shining clear, and when it was hidden by cloud. An amusing difficulty was encountered in an attempt to set on foot another inquiry. The Superintendent of the Meteorological Department at the time wished to have a measure of the rate at which evaporation took place, and therefore exposed carefully measured quantities of water in the open air in a shallow vessel. For a few days the record seemed quite satisfactory. Then the evaporation showed a sudden increase, and developed in the most erratic and inexplicable manner, until it was found that some sparrows had come to the conclusion that the saucer full of water was a kindly provision for their morning 'tub,' and had made use of it accordingly. A large proportion of the meteorological instruments at Greenwich and other first-class observatories are arranged to be self-recording. It was early felt that it was necessary that the records of the barometer and thermometer should be as nearly as possible continuous; and at one time, within the memory of members of the staff still living, it was the duty of the observer to read a certain set of instruments at regular two-hour intervals during the whole of the day and night--a work probably the most monotonous, trying, and distasteful of any that the Observatory had to show. The two-hour record was no doubt practically equivalent to a continuous one, but it entailed a heavy amount of labour. Automatic registers were, therefore, introduced whenever they were available. The earliest of these were mechanical, and several still make their records in this manner.