A friend of mine, then at Venice, again visited that city about five years afterwards. He subsequently informed me that he had purchased, at the manufactory I visited, samples of gold chains about an inch or two long, fixed on black velvet, and that it formed a regular article of trade in some demand.
A man may, without being a proficient in any science, and indeed with only the most limited knowledge of a small portion of it, yet make himself useful to those who are most instructed. However limited the path he may himself pursue, he will insensibly acquire other information in return for that which he can communicate. I will illustrate this by one of my own pursuits. I possess the slightest possible acquaintance with the vast fields of animal life, but at an early period I was struck by the numerical regularity of the pulsation and of the breathings. It appeared to me that there must exist some relation between these two functions. Accordingly, I took every opportunity of counting the numbers of the pulsations and of the breathings of various animals. The pig fair at Pavia and the book fair at Leipsic equally placed before me menageries in which I could collect such facts. Every zoological collection of living animal which I visited thus gained an additional interest, and occasionally excited the attention of those in charge of it to making a collection of facts relating to that subject. This led me at another period to generalize the subject of inquiry, and to print a skeleton form for the constants of the class mammalia. It was reprinted by the British Association at Cambridge in 1833, and also at Brussels in the 'Travaux du Congress Général de Statistique,' Brussels, 1853.
I have so frequently been mortified by having the utterly-
