"You can not tell. It would depend upon the distance. Suppose, then, the Rocky Mountains were half round the globe, how long would it take the sun to go to them?" "Suppose they were quarter round?"
"The whole distance is divided into portions called degrees—360 in all. How many will the sun pass in going half round?" "In going quarter round?"
"Ninety degrees, then, make one quarter of the circumference of the globe. This, you have already said, will take six hours. In one hour, then, how many degrees will the sun pass over?"
Perhaps no answer. If so, the teacher will subdivide the question on the principle we are explaining, so as to make the steps such that the pupils can take them.
"How many degrees will the sun pass over in three hours?"
"Forty-five."
"How large a part of that, then, will he pass in one hour?"
"One third of it."
"And what is one third of forty-five?"
The boys would readily answer fifteen, and the teacher would then dwell for a moment on the general truth thus deduced, that the sun, in passing round the earth, passes over fifteen degrees every hour.