I went to see Mr. Watts, keeper of the Apothecaries' garden of simples at Chelsea, where there is a collection of innumerable rarities of that sort particularly, besides many rare annuals, the tree bearing Jesuit's bark, which had done such wonders in quartan agues. What was very ingenious was the subterranean heat, conveyed by a stove under the conservatory, all vaulted with brick, so as he has the doors and windows open in the hardest frosts, secluding only the snow.