In some parts of India the natives have a very rude contrivance to mark the progress of time. A thin metal cup, with a small hole in its bottom, is put to float in a vessel of water; and as the water rises through the hole the cup sinks in a given time--in 24 minutes. A servant is set to watch the sinking of the cup, and when this happens he strikes upon a bell. Half a century ago, almost every cottage in England had its hour-glass--an imperfect instrument for registering the progress of time, because it only indicated its course between hour and hour; and an instrument which required a very watchful attention, and some labour, to be of any use at all. The universal use of watches or clocks, in India, would wholly displace the labour of the servants who note the progress of time by the filling of the cup; and the same cause has displaced, amongst us, the equally unprofitable labour employed in turning the hour-glass, and watching its movement. Almost every house in England has now a clock or watch of some sort; and every house in India would have the same, if the natives were more enlightened, and were not engaged in so many modes of unprofitable labour to keep them poor. His profitable labour has given the English mechanic the means of getting a watch. Machinery, used in every possible way, has made this watch cheap. The labour formerly employed in turning the hour-glass, or in running to look at the church clock, is transferred to the making of watches. The user of the watch obtains an accurate register of time, which teaches him to know the value of that most precious possession, and to economize it; and the producers of the watch have abundant employment in the universal demand for this valuable machine. A watch or clock is an instrument for assisting an operation of the mind. Without some instrument for registering time, the mind could very imperfectly attain the end which the watch attains, not requiring any mental labour. The observation of the progress of time, by the situation of the sun in the day, or of particular stars at night, is a labour requiring great attention, and various sorts of accurate knowledge. It is therefore never attempted, except when men have no machines for registering time. In the same manner the labours of the mind have been saved, in a thousand ways, by other contrivances of science.