A gentleman coming a passenger in a vessel from the West-Indies, finding it more inconvenient to be shaved than to wear his beard, chose the latter——but he was not suffered to have his choice long—it was the unanimous opinion of the sailors, and indeed of the Captain as well, that there was not the least probability of a wind as long as this ominous beard was suffered to grow. They petitioned—they remonstrated, and at last prepared to cut the fatal hairs by violence. Now, as there is no operation at which it is so much the patient’s interest to consent, as that of the barber——the gentleman quietly submitted—nor could the wind resist the potent spell which instantly filled all their sails, and “wafted them merrily away.”
You see we have only got rid of _general_ superstition, we still retain that which belongs to our particular profession or pursuits.
I have often tryed to have a proper idea of vast space—great numbers—enormous size and such subjects, and as you may suppose, without success. But though I fail in getting a competent idea, I sometimes make an approach towards it, which is better than nothing.
The solar system is one of these sublime subjects in the consideration of which I have frequently been lost. I never attempted to conceive the size of the sun, or the distance of saturn; the impossibility instantly repels the most daring imagination. No, all that I have attempted is to have a just idea of the proportion (upon any scale) that the sun and planets bear to each other in respect to size and distance. At first sight, this seems easily done—Draw some concentric circles on a sheet of paper, make the sun the centre, and place the planets round in their order.—Or if you would have an idea of their motion as well, look at an orrery. But a little examination will convince you that this is doing nothing towards having an idea of their size and distance in proportion to each other, which is the point sought. Nay, it is worse than nothing, for it imposes a falsity as a reality. Imagination by itself can do a great deal, if assisted it can do more, but if perverted, nothing. Let us try to assist the imagination then.
If the sun be only a million times bigger than the earth, (exactness is of no consequence to my argument, so that I am within the truth) it is plain that I cannot make two circles upon a sheet of paper (without considering any thing about distance) that can bear this proportion to each other; and if this cannot be done for the earth, much less can it for other planets and moons where the disproportion is greater. Let us take the floor of a large room—on this make a circle of two feet diameter for the sun—the size of the earth will be about a large pin’s head. The distance of the sun from the earth is about eighty of the sun’s diameters; if so, there must be a circle of three hundred and twenty feet diameter for the earth’s orbit, which no room, nor indeed any other building, will contain. Let us try a field——here we may put our sun and draw the earth’s orbit round. If we stand in the center (which we should do) the earth is too small to be seen. These difficulties occurring so soon, how will they increase when we take in the superior planets? The ingenious Ferguson has endeavoured to assist our imagination by supposing St. Paul’s dome, in diameter one hundred and forty-five feet, to be the sun——upon this scale, Mercury is between nine and ten inches, and placed at the Tower; Venus near eighteen, at St. James’s Palace; the Earth eighteen, at Marybone; Mars ten, at Kensington; Jupiter fifteen feet, at Hampton-Court; and Saturn eleven feet and half, at Cliffden. Let us be on the top of the dome, and look for the planets where he has placed them. Do you think we could see any thing of Jupiter and Saturn? to say nothing of their moons—or that we could conceive properly the difference between four miles and twenty, when seen on a line? the four may be two, or one mile; and the twenty may be ten, or thirty, for ought we can judge by the appearance. All that we get by this is the knowing that a sheet of paper or an orrery give us wrong ideas, and that we cannot by any contrivance put the size and distance of the planets upon a proportionable scale, so as to take in the whole with our eye or understanding.