Note 14 — Chapter IV
Reading edition
Newton speaks with singular positiveness on this subject. “For I know,” says he, “that Mr. Lucas’s observations cannot hold where the refracting angle of the prism is full 60°, and the day is clear, and the full length of the colours is measured, and the breadth of the image answers to the sun’s diameter; and seeing I am well assured of the truth and exactness of my own observations, I shall be unwilling to be diverted by any other experiments from having a fair end made of this in the first place.” On the supposition that his prism was one of very low dispersive power, Mr. Lucas might, with perfect truth, have used the very same language towards Newton.