 (Thomson would much later author the article for the 7th edition).The article "Electricity", 125 pages in the 3rd edition, was completely re-written for the 4th edition and was 163 pages.By contrast, the 125-page "Metaphysics" of the 3rd was largely unchanged for the 4th, and the 306-page "Medicine" of the 3rd was only superficially edited in the 4th and of roughly equal length.