THE BRAIN OF ANIMALS. Of all parts of the body of man to be well studied, the brain should be the most attractive. It is the place where all force centers, where all nerves connect to one common battery. By its orders the laboratory of life begins to move on crude material and labors until blood is formed and becomes food for all nerves first; then arteries and veins by nerve action and forces, to suit each class of work to be done by that set of nerves which is to construct forms; keep blood constantly in motion by the arteries and from all parts back to the heart, through the veins, that the blood may be purified, renewed and re-enter the arteries to be taken to all places of need. ARTERIAL MOTION. Arterial motion is normal during all ages, from the quick pulse of the babe's arm, to the ages of each year to one hundred or more. At this great age the pulse is so slow that the heat is not generated by the nerves, whose motor velocity is not great enough to bring electricity to the stage of heat. All heat, high and low, surely is the effect of active electricity--plus to fever; minus to coldness. When an irritant enters the body by lung, skin or any other way, a change appears in the heart's action from its effects on the brain, to the high electric action and that burning heat called fever. If plus violent type (yellow fever), if minus, low grades (typhus, typhoid, plagues), and so on through the list. MENTAL VIBRATIONS. To think implies action of the brain. We can grade thought although we cannot measure its speed. Suppose a person of one kind of business thinks just fast enough to suit that profession. A man is engaged in raising hogs and that alone. He must reason on and of the nature of hogs. He begins about so: a hog eats, drinks, bathes, roots and sleeps. He knows the hog eats grain, so he feeds it corn, or some other suitable cereal, with plenty of water and good bedding. The swine is on his mind night and day. THE WHEELS OF THOUGHT. Now the question is, how fast does he think? How many revolutions do the wheels of his head make per minute to do all the necessary thinking connected with the hog business? Say his mental wheels revolve 100 times each minute. Then he adds sheep to his business, and if that should require 100 more revolutions and he takes charge of raising draft horses with 175 revolutions added, you see the wheels of his head whizzing off 375 vibrations per minute. And at this time he adds the duties of the carpenter with 300 more revolutions, add them together and you see 675. To this number he adds the duties and thoughts of a sheriff, which are numerous enough to buzz his wheels at 1500 more, you find 2175 to be his mental revolutions so far. Now you have the great physical demands added to the mental motion which his brain has to support, yet he can do all so far, fairly well. OVERBURDENING THE MIND.