A disease which, though unquestionably common to this country from remote time, has only within the last thirty years obtained a distinctive name and character. What the peculiar state of the atmosphere is, that induces or predisposes to this disease, science has not yet discovered, though the external causes, as far as appreciation enables us to form an opinion, appear to be, a long-continued state of humidity, succeeded by sudden heats, or seasons of alternate hot and wet weather, or a long humid autumn followed by a cold and boisterous winter. In these conditions of the climate the disease often becomes epidemic and puts on a protean shape, and, though twenty persons in the same tenement are attacked with it, not two perhaps present the same chain of symptoms, or have been seized in the same way. The first sign of illness in one is a sudden coma, that deprives the patient for some minutes of all consciousness; another falls in a fit, a third is seized with an intense pain on the top of the head, others by fits of sudden heat or cold, by coughing, or pains in the back, chest, or throat; but however varied the commencement may be, or different the general run of symptoms, there are three signs that, taken together, always characterize influenza, and by which it may in every case be at once identified; these are—severe and splitting pain on the top of the head, great and sudden loss of strength, and a rough excoriated sensation in the chest behind the breast-bone, as if the lining membrane in that part was raw. When influenza comes on gradually, the disease generally puts on the following succession of SYMPTOMS: a sense of cold, lassitude, weariness, cold chills, pains in the back, head, and loins; these symptoms are followed by flushings, weight on the head and a great oppression on the chest, sneezing, the eyes become bloodshot, a thin acrid discharge from the nostrils occurs, with inflamed fauces and throat, followed by a short cough with a thick viscid expectoration, which soon becomes thin, discoloured mucus, mixed with purulent discharge. With these symptoms there is extreme prostration of strength, loss of energy, and great depression of spirits, the pain on the head continuing with unabated violence. The pulse, which at the beginning was quick and small, becomes, as the disease progresses, sharp, weak, and irregular. From the first the appetite has failed, the tongue furred, and the stomach in a state of nausea and often irritated to vomiting. The discrepancy in the state of the pulse in influenza generally renders it an insecure guide to a knowledge of the heart’s action by the number or the frequency of the beats; the only true test of the vital strength of the patient is, the amount of pressure by the finger the pulse will bear. Influenza, if not speedily cured, is very prone to degenerate into bronchitis, pneumonia, pleurisy, or some chronic thickening of the mucous membrane of the throat, or enlarged tonsils.