Having commenced and terminated our description with the right side of the heart, we have briefly traced the circle (if I may so term it) of the circulation; and will now proceed, as briefly, to direct the reader's attention to a few of the most convincing evidences of the design and wisdom of the grand Contriver of these things.

To prevent the blood returning from the ventricles to the auricles whence it came, it was necessary that there should be valves, so constructed as to close the opening, when, by the contraction of the sides of the cavities, the blood would be as likely to be driven back again into the auricles as into the vessels arising from the ventricles. Again, to prevent the blood regurgitating into the ventricles on their dilating, after the blood has been propelled into the large arteries arising from them, it was necessary that the origin of the vessels should be closed by valves. The construction of these valves is such as most admirably to answer the desired object. They are composed of a thin fold of membrane, lying in close contact with the sides of the vessels, and thus allowing a free passage for the blood when proceeding onwards; but expanding and effectually closing the apertures, after the fluid has been propelled into them. This expansion is effected by the edges of the valves being directed towards each other by the blood being forced between the membrane and the sides of the

In man, the heart at every contraction expels about two ounces of blood; and, if we calculate that there are eighty such contractions in a minute, there must be one hundred and sixty ounces sent forth by it in that space of time; and in about three minutes, the whole blood in the circulation, averaging about thirty pounds, must pass through the heart; and, in the space of one hour, this must necessarily take place twenty times.

To extend this interesting subject still farther, let us suppose that two ounces of blood will occupy a cylinder eight inches in length; then it will pass through six hundred and forty inches in a minute; and thirty-eight thousand four hundred inches, or three thousand two hundred feet, in an hour!

The impulse of the heart's contraction is conveyed along the arteries to the most remote parts of the body; and the number of these contractions is thus accurately indicated by the pulse at the wrist. The number and force of these pulsations is influenced by a great variety of circumstances; but we will suppose seventy in a minute to be the average number. If the pulse of an individual beat seventy times in a minute, it will beat one hundred thousand eight hundred times in a day, and thirty-six millions eight hundred and sixteen thousand four hundred and twenty-six and a half times in a year. Yet this incessant action may be continued year after year through a long life, without impairment of the structure of the heart, and without any signs of disorder or weariness. We cannot reflect without admiration that such thin and delicate instruments as the valves of the heart should be able to hold out under this unintermitting action, during a period of seventy or eighty years, without the slightest derangement of their structure, or inconve

nience to the individual. Sincerely should every one exclaim, on beholding this instance of divine wisdom and goodness, "I will praise thee, O Lord; for I am fearfully and wonderfully made." Indeed, it would be difficult to point to one part of the human body to which the exclamation of the Psalmist would more appropriately refer, than to the valvular apparatus of the heart. These valves were required to be powerful, in order to withstand the considerable resistance afforded by the blood, continued so unceasingly and for so protracted a period; yet they were required to be delicate and thin, in order that they should occupy but small space, and consequently afford but slight obstruction to the passage of the blood, when they were not required to close the apertures. To all human appearance, they are not calculated to overcome so considerable and protracted resistance as we really find they do; and it is a source of astonishment, that they are not by far more frequently the seat of disease than they really are. Hence, it may emphatically be said, in reference to the structure of the heart, that we are "fearfully," as well as "wonderfully, made."

One other reflection connected with the number of the heart's pulsations in a minute, in a day, in a year, rushes into the mind,-that every heart will cease to beat!

"Our wasting lives grow shorter still,

As days and months increase; And every beating pulse we tell Leaves but the number less." If we reflect that the heart of every individual has an allotted number of pulsations to perform, and that it is hastening to the fulfilment of its appointed course by such strides as one hundred thousand eight hundred strokes every day, four thousand two hundred every hour, and seventy every minute of our lives, we must surely be impressed with the fleetness of life, and the rapidity -of our approach towards death!

"The utility of the circulation of the blood," writes Paley, in his invaluable work on Natural Theology,

"I assume as an acknowledged point. One grand purpose is plainly answered by it; the distributing to every part, every extremity, every nook and corner of the body, the nourishment which is received into it by one aperture. What enters at the mouth, finds its way to the fingers' ends. A more difficult mechanical problem could hardly, I think, be proposed, than to discover a method of constantly repairing the waste, and of supplying an accession of substance to every part of a complicated machine, at the same time.

"This system presents itself under two views: first, the disposition of the blood-vessels, that is, the laying of the pipes; and, secondly, the construction of the engine at the centre, namely, the heart, for driving the blood through them.

"The disposition of the bloodvessels, as far as regards the supply of the body, is like that of the waterpipes in a city; namely, large and main trunks branching off by smaller pipes (and these again by still narrower tubes) in every direction, and towards every part in which the fluid, which they convey, can be wanted. So far the water-pipes, which serve a town, may represent the vessels which carry the blood from the heart. But there is another thing necessary to the blood, which is not wanted for the water.; and that is, the carrying of it back again to its source. For this office, a reversed system of vessels is prepared, which, uniting at their extremities with the extremities of the first system, collects the divided and subdivided streamlets: first, by capillary ramifications into larger branches; secondly, by these branches into trunks; and thus returns the blood (almost exactly inverting the order in which it went out) to the fountain whence its motion proceeded. All which is evident mechanism.”*

The difference of structure of the two systems of blood-vessels, arteries, and veins, is exactly adapted

• Natural Theology, vol. i., p. 141, Paxton's illustrated edition.

part of the system, and the veins converging towards the heart from the body; recollect the calculations which have been given of the number of the heart's pulsations, and of the quantity circulated through the system, that the entire quantity of blood contained in the system (about thirty pounds) is circulated through the body about twenty times within the hour; and, lastly, consider," with Paley, "what an affair this is, when we come to very large animals. The aorta of a whale is larger in the bore than the main pipe of the water-works at London bridge; and the water roaring in its passage through that pipe, is inferior in impetus and velocity to the blood gushing from the whale's heart." Hear Dr. Hunter's account of the dissection of a whale: "The aorta measured a foot diameter. Ten or fifteen gallons of blood are thrown out of the heart at a stroke, with an immense velocity, through a tube of a foot in diameter. The whole idea fills the mind with wonder." Observe these facts, we repeat, and what must be the feelings of that individual who can think of them without admiring wonder?

*

"The wisdom of the Creator," saith Hamburgher, “is in nothing seen more gloriously than in the heart;" and for the purpose of making this interesting subject somewhat more generally known, of thus supplying a small share of information with which the impetuous, and, it is to be feared, increasing torrent of infidelity may be, to a slight extent, met and combated, as well as of directing individuals to other sources of information to the same end, are these brief essays humbly written. Infidelity, with such monstrous concomitants as Socialism, is now rampant, stalking forth in the broad light of noon-day, with unblushing

The water-works of the time in which Paley wrote.

+ Natural Theology, vol. i., p. 150.

effrontery, and should be grappled with by every one capable of lifting his voice in public, or of wielding his pen in private; manifesting itself, as it does," in the dark, unsettled spirit of him, whose every reflection is tinctured with gall, and who casts his envious and malignant scowl at all that stands associated with the established order of society."

The sentiment of the most classical of our living poets, that

"Coming events cast their shadows before,"

seems strikingly to have been exemplified in the above-quoted passage from Dr. Chalmers, which, as if allusive to some such iniquitous system as the Socialism of the present day, would appear to have been written with a prophetic pen. This most wicked system, if system it may be called, by denying the being of a God, the existence of Providence, and a moral government, aims at the subversion of all religion, and is calculated to brutalize the human character. Every voice and every hand should be raised against an evil of such fearful magnitude.

What being, possessed of reason and reflection, can retire from the investigation of the course of the blood in our frames, without being convinced that each part of this mortal body has been created with an evident design? Having once knowledged the existence of design, he must admit the pre-existence of a Designer, who, from the stupendous and overwhelming magnitude of the task, must be omnipotent; who, from the harmony and mutual dependence of the whole, must be omniscient; and from these unique and combined attributes, MUST BE GOD!