here credits him with, unless after the elements have melted with fervent heat, the new heavens and a new earth are to be interpreted as made respectively of air and earth! [Sidenote: His own knowledge of science.] We may agree at least with Wright that Neckam’s scientific attainments are considerable for his time. In physics and astronomy he shows himself fairly well versed. He knows something of vacuums and syphoning; he argues that water tends naturally to take a spherical shape;[591] he twice points out that the walls of buildings should not be exactly parallel, since they should ultimately meet, if prolonged far enough, at the center of the earth;[592] and he asserts that the so-called “antipodes” are no more under our feet than we are under theirs.[593] He gives us what is perhaps our earliest information of some medieval inventions, such as the mariner’s compass and mirrors of glass.[594] But he does not attempt to explain differences in the images in convex and concave mirrors.[595] He is modest in regard to his biological attainments, saying that he “is not ashamed to confess” that there are species of which he does not even know the names, to say nothing of their natures.[596] But when Wright calls Neckam’s account of animals “a mere compilation” and says that “much of it is taken from the old writers, such as Solinus, Isidore, and Cassiodorus,”[597] he is basing his conclusion simply on the fact that marginal notes in the medieval manuscripts themselves ascribe a number of passages to these authors. This ascription is correct. But there are many passages on animals where the manuscripts name no authorities, and with one exception--the chapter on the hyena from Solinus--Wright fails to name any source from which Neckam has borrowed these other passages. It is easy to show that Neckam is a compiler when he himself or others have stated his authorities but it is equally fair to suppose that he is honest and original when he cites no authorities or has not been detected in borrowing. And he sometimes criticizes or discriminates between the earlier writers. After quoting Bernard Silvester’s statement that the beaver castrates itself to escape its hunters, he adds, “But those who are more reliably informed as to the natures of things assert that Bernard has followed the ridiculous popular notion and not reached the true fact.”[598] Neckam also questions the belief that a lynx has such keen sight that it can see through nine walls. This is supposed to have been demonstrated experimentally by observing a lynx with nine walls between it and a person carrying some raw meat. The lynx will move along its side of the walls whenever the meat is moved on the other side and will stop opposite the spot where the person carrying the meat stops. Neckam does not question the accuracy of this absurd experiment, but remarks that some natural scientists attribute it rather to the animal’s sense of smell than to its power of vision.[599]