Philosophical Transactions of the Royal Society is a scientific journal published by the Royal Society. In its earliest days, it was a private venture of the Royal Society's secretary. It was established in 1665, making it the first journal in the world exclusively devoted to science, and therefore also the world's longest-running scientific journal. It became an official society publication in 1752. The use of the word philosophical in the title refers to natural philosophy, which was the equivalent of what would now be generally called science. Current publication In 1887 the journal expanded and divided into two separate publications, one serving the physical sciences (Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences) and the other focusing on the life sciences (Philosophical Transactions of the Royal Society B: Biological Sciences). Both journals now publish themed issues and issues resulting from papers presented at the scientific meetings of the Royal Society. Primary research articles are published in the sister journals Proceedings of the Royal Society, Biology Letters, Journal of the Royal Society Interface, Interface Focus, Open Biology and Royal Society Open Science. Origins and history Origins The first issue, published in London on 6 March 1665, was edited and published by the Society's first secretary, Henry Oldenburg, four-and-a-half years after the Royal Society was founded. The full title of the journal, as given by Oldenburg, was Philosophical Transactions, Giving some Account of the present Undertakings, Studies, and Labours of the Ingenious in many considerable parts of the World. The society's council minutes dated 1 March 1664 (in the Old Style calendar; equivalent to 11 March 1665 in the modern New Style calendar) ordered that "the Philosophical Transactions, to be composed by Mr Oldenburg, be printed the first Monday of every month, if he have sufficient matter for it, and that that tract be licensed by the Council of this Society, being first revised by some Members of the same". Oldenburg published the journal at his own personal expense and seems to have entered into an agreement with the society's council allowing him to keep any resulting profits. He was to be disappointed, however, since the journal performed poorly from a financial point of view during his lifetime, just about covering the rent on his house in Piccadilly. Oldenburg put out 136 issues of the Transactions before his death in 1677. The familiar functions of the scientific journal—registration