“No matter how quick he might make it. It would take some time, wouldn’t it?”
“Only a very little,” said Rollo.
“And do you suppose the sun would stand still, even during that little time, so as to let the shadow remain stationary?
“However,” continued his father, “I don’t say this to disparage Jonas’s noon mark. I dare say, it is accurate enough for his purposes. He only wants to know from it when it is time for him to come in to dinner, or something like that. I only want you to understand what exactness is, and to see, a little, how difficult it is to attain to any considerable degree of it, in such cases. So thus, it seems, that Jonas has got a sort of a dial?”
“Why, it only tells him what o’clock it is at one hour in the day,” said Rollo. “But I think he might make it do for all the afternoon and forenoon.”
“How?” inquired his father.
“Why, all he has got to do is to watch some day when it is nine o’clock, and ten o’clock, and so on, every hour; and then make a line where the shadow comes every hour, just as he did for twelve o’clock. Then he will have marks for every hour in the day, and when the shadow comes along to these marks, one after another, he will know what time it is.”
“O, but the difficulty is,” said his father, “that the shadow will not come to the same places, at the same hours, on different days. It will come to the meridian line, at twelve, always,—that is, nearly to it; but it will not come to any other lines regularly,—that is, if the object, which casts the shadow, is upright.”
“Will any other kind of object carry the shadow regularly?” asked Rollo.
“Yes,” said his father, “an object that leans over to the north, so as to point to the North Star. If you and Jonas could put a post into the ground so as to have it point to the North Star, then you could mark, all around it, the places to which the shadow would come for every hour in the day, and afterwards it would come to the same places regularly, or nearly so. It would be near enough for your purposes; and I don’t know but that it would be quite a respectable dial for you.”