Traditionally, of course, we have five senses—sight, hearing, touch, taste and smell. Yet we sometimes say that we are “frightened out of our seven senses,” as if there were seven and not five. Really, the number of our different ways of feeling is neither five nor seven, as we shall now see by counting them up for ourselves.

Five at least we are sure of, the traditional five. There is no need for anyone to tell us what our eyes, ears, and noses are for; nor that we taste with our mouths as well as talk and eat, nor that we feel touches anywhere over our skins. As to this last, however, I don’t think we always realize how completely the sense of touch is confined to the skin. Headaches, for example, we feel on the outside of the head; the brain itself can be pinched, cut, burned, and generally maltreated, and we not feel it so much as we feel a pinprick on a finger tip.

Do you remember how, a few years ago, when you had not so many things to do as you have now, you used to amuse yourself by whirling rapidly round in one direction, till you were dizzy and could hardly stand up. For a few moments, or till you whirled around in the other direction, you lost your sense of right-side-up-ness; you didn’t know sky from ground; and if you had been whirling especially fast or long, you probably fell down flat, and couldn’t get up again. When you dance, too, without reversing, by and by you get giddy, the floor begins to curl up at the edges, and you become uncertain as to which way is down.

The trouble is not with the eyes, because we get dizzy with our eyes shut. We really have a sense of up and down, which is neither sight, hearing, touch, taste nor smell; but a sixth sense. Its organ is a portion of the inner ear, the so-called labyrinth; and it tells us, not how things look or sound or taste or smell or feel, but whether we ourselves are right side up. Too much whirling upsets this sense of equilibrium, just as too bright a light dazzles the eyes, or too loud a sound stuns the ears. A shark will swim with his head cut off; but his ears being gone, he is as likely as not to swim upside down.

There, then, are six senses. Let us see if we can find number seven. While you are sound asleep at night, you do more or less turning over in bed, so that in the morning, you are lying in quite a different position from that in which you went to sleep. Yet altho you remember nothing of what you did in the night, when you awake in the morning, and before you open your eyes, you can tell exactly the position of every arm, leg, or finger. You know just how much each joint is bent. You have, in short, a sense of where the several parts of your body are, which is none of the six senses which we have recognized heretofore.

So, too, if you shut your eyes, and let some other person move any member into another position, you feel it move, and know all the while just where it is. Or suppose you are playing short-stop, and fielding a hot grounder. Your eye is on the ball, and your mind on the game; but your hands drop, and your back bends, and your knees sink, all to precisely the right degree to bring your hands where the ball is. You have a most accurate sense of where these hands are, tho you neither see nor hear nor touch nor taste nor smell them. A piano player relies on this same muscular sense, when without looking at the keyboard he skips unerringly from one note to another, never going too far nor stopping too short. In fact, this muscular sense is really one of the most accurate of all our senses. We can see a speck of dust much too small to feel; but a person used to using a microscope or doing other nice work, can make a movement with his fingers as small as the twentieth part of the width of a hair—and that is a good deal smaller than any unaided human eye can possibly see.

As you might guess from its name, this muscular sense is located partly in the muscles. Still more, however, do we depend on the joints. We do not feel one bone slip over the other, that would be plain touch; but we know with extraordinary accuracy just how far the joint has moved and just where it is at any moment.

Here then are seven senses; now for number eight. Take something not too sharp, a tooth-pick will do, or the point of a lead pencil, and touch the skin lightly on the back of the hand or on the forehead or near the elbow. You feel, of course, the touch. Now move the point ever so little, by the thickness say of a small pin, and touch again. You probably feel the same touch as before. Continue this touching, and before you have tried twenty times, you ought to discover a spot where the point feels suddenly cold. In short, some points on the skin feel pressure, which is the ordinary sense of touch. But other points feel cold, which is a different sense, an eighth sense, and not touch at all.

There is also a ninth sense, the sense of heat. If you are very careful indeed, and notice very closely, you can find heat spots, just as you found the cold spots. Only these are much harder to locate, so that you will probably not be able to make them out.

One more sense is located in the skin besides these three. That is the sense of pain. Tho to be sure other parts of the body feel pain also—the muscles and joints when we have rheumatism, and the teeth when we have the tooth ache. Pain is not touch. In the first place it feels very different, and in the second place, it is quite possible to lose one sense and keep the other. In certain diseases of the nerves, the ordinary sense of touch remains as before, but the sense of pain completely disappears. One can be pinched, cut, burned, in the most violent manner, feel the touch of fingers or knife or hot wire, and yet not feel the slightest pain. And the same thing is true, after one has taken the right amount of ether or chloroform; one isn’t asleep, and one can feel touches but one does not feel pain—and a wonderful blessing it is sometimes.

I wonder whether many of you have ever heard of cocain, or had it used on you when you got something in your eye, or had to have something done to the inside of nose or mouth. (Only you musn’t call it “co-cane,” in two syllables, as many people do and as it looks in print, but “co-ca-in,” in three syllables; for it is extracted from coca leaves, and the name is “coca,” with the “in” added on, like strychnin, atropin, protein, and the names of so many drugs and medicines). Cocain, then, looks a good deal like common salt, but fit grain or two in a drop of water, placed anywhere where the skin is thin, soaks thru to the ends of the nerves, and for ten minutes or so, puts an end to all feeling there. If now we apply cocain to the tongue in just the right strength, it takes away for the moment all sense of pain, while it leaves the sense of taste as before, and the sense of touch. One can bite his tongue and feel the bite, yet it does not hurt. One can drop hot syrup on it, taste the sweet, and yet not feel the burn. But if we make the cocain a little stronger, then when the pain goes, the taste goes with it. One can feel something in his mouth, but cannot tell sugar from salt; while a drop of strong acid, tho it burned a hole in the tongue, would neither taste sour nor hurt. A still stronger dose of the drug suspends all feeling—pain, taste, and touch alike.

So pain is a different sense from touch, just as much as taste is. Besides, if you take a sharp pin and make a line of pricks close together, much as you did when hunting for cold spots, taking pains to prick equally hard each time, you will be pretty sure to discover certain points where the prick hurts much more than it hurts the thickness of the pin away. This, of course, is a pain spot. Between these you hardly feel the pain at all.

There are, then, in the skin, cold spots, hot spots, touch spots, and pain spots, from two to three times as many of each as there are fine hairs on the skin. Under each of these spots, is the end of a nerve, either branching like a little bush or ending in a sort of oval knob, much the shape of a foot ball. And just as the eye sees, but doesn’t hear, and the ear hears, but doesn’t see, so each of these nerve endings feels either pain, or cold, or heat, or pressure, but only one of them.

How many senses have we then? At least ten, which is twice the traditional five. Besides these there are thirst and hunger, which are certainly feelings, tho neither sight, hearing, touch nor any of the rest. Then there is that peculiarly unpleasant feeling which comes to us after we have dined less wisely than well, or have been rocked too fondly in the cradle of the deep, the sensation, I mean, which we call “sickness” or nausea. This makes thirteen senses. There are several more in addition to these, more or less vague affairs, which for the most part tell us only what is going on inside our own bodies.

If therefore, you ask how many senses we really have, I shall have to say that we had better call it ten. At least we have ten well defined sorts of feelings, which tell us what is going on outside our bodies—and after all, that is what senses are for. These, then, will be sight, hearing, touch, taste, smell, heat, cold, pain, equilibrium, and the muscular sense. Each of these has its own special place, in eye, ear, joint between two bones, or little spot in the skin. If we lacked any one of these (as indeed many creatures do) there would be something which it is important for us to know, but which would be forever impossible for us to find out.