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The Study at Woolsthorpe Manor
The room to the right of the staircase at Woolsthorpe Manor is now called the Study. As with the other rooms in the house, it now contains period furniture, although none of it is original. The door is on the north wall and there is a medium size window to the west. In the south wall is another small window. The southeast corner is partitioned off by an eighteenth century wooden screen. Inside this are a marble bust of Newton and a copy of the third edition of Principia, published in 1727.
The account of one of Newton's prism experiments suggests he carried out optical investigations at Woolsthorpe during the Plague Years. The seventh experiment from his paper Of Colours describes an experiment in which a spectrum is cast on a wall using a prism. The sunlight enters a darkened room through ``a little round hole'' and the prism is placed close to this. An elongated image with the colours of the rainbow was produced on the far wall. Newton recorded the distance from the wall to the prism to be 260 inches.
The distance between the south and north walls of the study is 243.5 inches. There is a small south window which is currently covered by a shutter. The distance from this board to the opposite wall is 260 inches within about half an inch. (I made this measurement myself when I thought the prism to wall distance in Newton's notes was 264 inches - ie 22 feet exactly. One of the complications was the wooden partition which is now between the window and the opposite wall. Luckily there was a gap between the panels large enough to thread a tape measure through.)
If the distance from the wall to the window in the room Newton did this experiment was 260 inches, then the distance to the prism would have to be slightly less. However, we could speculate that Newton was satisfied by substituting the wall to window distance for the true wall to prism distance.
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