But though it is perfectly plain that badly ventilated sleeping apartments tend greatly to the production of diseases of the lungs, it is not generally understood by the greater number of persons that diseases of the heart are brought on by similar conditions, and there is without doubt a great increase of heart diseases at the present time. It is estimated that upwards of 10,000 people in England alone die yearly from affections of the heart; yet, taking into consideration the ceaseless work of that organ (in the words of the motto upon Goethe's ring, "Ohne Rast"--without rest), it is wonderful that it is not more frequently diseased. It is said that "the heart is a small muscular organ weighing only a few ounces, beating perpetually day and night, morning and evening, summer and winter; and yet often an old man's heart nearly a hundred years of age is as perfect and complete as when he was a young man of twenty" (Haughton). The effect of impure air in its action on the heart is thus spoken of by Dr. Cornelius Black: "I showed the effect of impure air in promoting the degenerative tendency in the structures of the heart, and especially those of the right side of the heart, after the age of forty. I was then led to a passing consideration of the baneful influence produced upon the heart by badly-ventilated houses, schools, manufactories, pits, theatres, underground railways, and all places of a similar character." "The impure atmosphere of the bedrooms of the poor, and indeed of many of the middle class, caused by deficient ventilation, proves a sharp spur to the degenerative tendency manifested by the heart, and especially by the right side of the heart, after the age of forty." "I hold that the breathing of impure air is a fruitful source of disease of the right side of the heart occurring after middle age. How many people ignorantly favour its occurrence by confining themselves to closely shut, non-ventilated, stuffy, sitting rooms, in which the carbonic acid has accumulated to a poisonous degree in the air they respire! How are these evil results to be prevented? The simple answer is, let the rooms in which you live be effectively ventilated by an incoming current of fresh air, and so arranged that no draught shall be felt."