"For the greater beauty of the instrument, the balls representing the planets are to be of considerable bigness; but so contrived, that they may be taken off at pleasure, and others, much smaller, and fitter for some purposes, put in their places"

This quote by David Rittenhouse is referring to an astronomical instrument, likely a model of the solar system. He is suggesting that the planets should be represented by big balls, but that they should be able to be removed and replaced with smaller balls that are more suitable for certain functions. This recommends that the instrument is meant to be both visually pleasing and practical. The larger balls would make the instrument more aesthetically enticing, while the smaller sized balls would be more useful for particular jobs. Rittenhouse's quote highlights the importance of both form and function in the design of the instrument. He is suggesting that the instrument should be developed in such a way that permits it to be both aesthetically pleasing and beneficial. This quote is a tip that appeal and practicality can exist side-by-side in the same style.