The hansom cab was originally a marvellous novelty. In the language of breeders it was a sudden and remarkable "sport," yet the suddenness of its appearance has been no bar to its unchanging hold on popular favour. It is not a monstrous anomaly of incongruous parts, and therefore unstable, but quite the contrary. Many other instances of very novel and yet stable inventions could be quoted. One of the earliest electrical batteries was that which is still known as a Grove battery, being the invention of Sir William Grove. Its principle was quite new at the time, and it continues in use without alteration. . . . It seems to me that stability of type, about which we as yet know very little, must be an important factor in the general theory of heredity, when the theory is applied to cases of high breeding. . . .
Infertility of Mixed Types.--It is not difficult to see in a general way why very different types should refuse to coalesce, and it is scarcely possible to explain the reason why, more clearly than by an illustration. Thus a useful blend between a four-wheeler and a hansom would be impossible ; it would have to run on three wheels and the half-way position for the driver would be upon its roof. A blend would be equally impossible between an omnibus and a hansom, and it would be difficult between an omnibus and a four-wheeler .* [emphases mine]
Strangely, the copy of Galton's Natural Inheritance available in PDF form at archive.org is from Harvard's divinity school of all places. The college's library stamp represents the testament of Christian scripture as an open book, with Psalm 119:169 cited on the left side and John 17:17 cited on the other. The Hebrew words of the Psalm say "in Your word give me understanding," and the Greek words from the Gospel say "Your word is truth."