study, set his papers on fire, and destroyed the labours of many years. The great philosopher shewed an equanimity worthy of his fame, when his only remark on the catastrophe was, "O Diamond, Diamond, thou little knowest the mischief thou hast done!" M. Lescarhault's but was nearly as fatal to the discovery he was on the brink of making. At the most interesting moment of the observation, a knock was heard on the counter of the laboratory below. He listened for a moment without moving. The knocking became more emphatic; it was a patient demanding medical relief. He would fain look on, and follow the dark spot rapidly travelling across the sun's disk. But it may not be. The call of duty must be obeyed,* and no villager could say that the good doctor ever forgot his patients in his devotion to the stars. Fortunately, it was not a call to go abroad. A soothing draught was all that was needed. He scrupulously measured out the ingredients, corked and labelled the bottle; and not till then did the conscientious doctor feel at liberty to rush up to his little observatory, and eagerly apply his eye to the telescope. It is not too late; the strange planet is still upon the disc.
He marked precisely the time when he saw it near the eastern edge. He must now carefully watch the moment when it leaves the disc. Having noted these times, and measured the size and position of the segment of the sun's disc cut off by the path of
