"In no other fields are large and important truths so distinctly related to human interests so readily traced; yet the treatises dealing with these truths are few in number and generally recondite."] What here appear as chapters were originally little talks for the evening entertainment of the juvenile members of a certain family and the neighboring children, who were attracted by what came to be known as the "pebble parties," during the season at Mount Desert Island. They are here given in substantially the form in which they first saw the light. While they proved entirely intelligible to boys and girls of eight and ten they seemed equally interesting to the older members of the audience, including a youth of eighteen in his last year of high school, whose comments, in the language of his caste, deserve to share the credit for whatever of whimsical humor and colloquial style the author may have succeeded in incorporating into the narrative. The familiar tone, the number and variety of the chapters, the sub-heads and marginal captions and the character and treatment of the illustrations have a similar origin. They represent the variety of aspects under which it was found necessary to present the facts in order to hold a capricious audience whose attendance and attention were wholly voluntary. The use of unfamiliar words and scientific terms has been avoided as much as possible, consistent with the educational purpose of the book. It is to be remembered that educators do not consider it good practice to omit all words which children cannot understand at sight; the theory being that it is by the judicious introduction of words not current on the playground that the intellectual interests and capacities of children are enlarged. With regard to scientific topics (it is further argued) a large proportion of the classics of science written for the general reader and which boys and girls of fourteen and upward should be able to read easily and with pleasure--Shaler, Darwin, and Wallace, for example--contain quite a few scientific terms; and these it would be well that young people learn from context or definition in their previous reading in works of a more elementary nature. Moreover, while younger children will read a book the general character of which interests them, even though they do not understand every word or get all the thoughts in it, sophisticated youths of the high-school age will have none of it, if they suspect that they are being talked down to. In the story of the pebble the aim, accordingly, has been not only to make a book that young people will not outgrow but one that will be of some interest to adults, particularly to travellers.