} There are about three thou Every astonishing works of the divine architect. sand fixed stars visible by the naked eye. Every one of those stars is doubtless a sun, and each of those suns affords light and heat to another system of worlds. Let us only suppose that each of those suns illuminates as many orbs as belongs to our system. We shall state the number at two hundred, though it is believed that twice this number of comets, beside the planets, have already been discovered. This would give three hundred thousand worlds. But three thousand is a small number when compared with the whole number of stars that have been discovered. The relative places of fifty thousand stars have been determined by the help of telescopes. Fifty thousand solar systems, each containing at least one hundred worlds. Five millions of worlds all inhabited by rational beings. How do we seem to dwindle into littleness. How small, how few, are the ephemerons of this little globe, when compared with the countless myriads who inhabit five millions of worlds? All those worlds, and every one of their inhabitants, are under the constant care of the Divine Being. Not one of them is neglected. Great and marvellous" are his works. How terrible his power! No. II. OBSERVATIONS on the Laws governing the Communication of CONTAGIOUS DISEASES, and the means of arresting their progress. By DAVID HOSACK, M. D. Professor of the Theory and Practice of Physic and Clinical Medicine in the University of the State of New-York, &c. [Read before the Society, 9th June, 1814.] In July, 1808, I addressed to Dr. Chisholm some observations on contagion, or infection.* The object of that communication was, if possible, to narrow the ground of controversy upon that important and much contested subject. This I endeavoured to do, first, by showing that the distinction which had been proposed by some late writers, between contagion and infection, was unnecessary and fallacious; secondly, by dividing all diseases which are contagious, infectious, or communicable from one person to another, into different classes, according to the several laws which appear to govern their communication. These classes are three in number. The first embracing those diseases which are communicated exclusively by contact; as the itch, syphilis, hydrophobia, &c. which are never conveyed through the medium of the atmosphere. The second including those diseases which are communicable both by contact, or the near approach to the sick, and by the atmosphere, as measles, small-pox, scarlet fever, &c. which are communicable in every season of the year, and in every climate; in a pure as well as in an impure * See Edinburgh Med. and Surg. Journal, vol. 5. p. 247. American Medical and Philosophical Register, vol. 2. p. 14. air, though more readily by means of the latter than the former, and with which persons are rarely infected more than once in their lives. Under the third class are enumerated those diseases which are only, in general, communicable, or contagious through the medium of an impure atmosphere; the air being rendered thus impure by the decomposition of animal and vegetable substances, as in low, marshy countries; or by concentrated human effluvia, as in camps, jails, hospitals, or on shipboard; but the same diseases I alleged, in a pure air, in large and well ventilated apartments, when the dress of the patient is frequently changed, all excrementitious discharges constantly removed, and attention paid to cleanliness in general, are not usually contagious, or, under such circumstances, are very rarely communicated from one person to another. In this class I included the plague, dysentery, typhus fever, in its various forms, of jail, ship, hospital, or lake fever, and the yellow fever. I also remarked, that these diseases, like many of the first class, may be repeatedly contracted; but that they are communicable, or otherwise, according to the condition of the air in which they occur, or into which they may be introduced: it was further observed, that the atmosphere thus impregnated by the peculiar virus emanating from the diseased body, becomes assimilated to the poison, or ferment introduced, and thereby is rendered capable of reproducing in others the same specific disease, whether it be the plague, dysentery, typhus, or yellow fever. Such are the outlines of my first communication to Dr. Chisholm.* In 1809 Dr. Chisholm did me the honour to reply† to my observations, expressing his entire approbation of the two first classes, but See Note A. See American Medical and Philosophical Register, vol. 2. p. 121. See Note B. objecting to the third. After enumerating his several objections, he requests me to reconsider my third division, which appears to him to be the only objectionable one. This I have done, and now submit to this society the result of a further examination of this subject, and a detail of the facts by which I have been led to my conclusion relating to the laws of communication, which I have more particularly assigned to the febrile diseases enumerated in the third class. To In my first communication, I acknowledge I have stated my observations without so full a detail of the facts themselves whence my conclusions were deduced, as perhaps ought to have been exhibited. the European reader, unacquainted with the peculiarities of yellow fever, more especially as it has appeared in the cities of the United States, my first statement may perhaps appear defective in that evidence which is so justly exacted upon subjects of this nature. This evidence I shall now endeavour to supply, and thereby to confirm the correctness of the classification which has been proposed. Waiving for the present all inquiry relative to the nature or properties of the contagious principle secreted by the diseased body, or the chemical qualities of the atmosphere deemed necessary for its propagation, or the manner in which the contagion diffuses itself, I proceed to observe, that the history of each disease enumerated in the third class, viz. plague, dysentery, typhus, in all its forms, and yellow fever, furnishes evidence of the correctness of the remark, that they are governed by a law peculiar to themselves, that they are contagious or communicable in a foul atmosphere, but that they are never or very rarely so in a pure air, where the sick enjoy the benefits of cleanliness and ventilation. The same evidence, I trust, will demonstrate another truth, that these diseases are, in no instances, epidemic, as they have been improperly denominated by most practical writers, but that their sphere of operation is, with very few exceptions, confined within the limits to which |