Dr. Alexander Melville Bell has shown, in his work on "Visible Speech," that the organs brought into use in the production and modification of sounds must work in harmony with each other; hence it is that by a study of the external forms of the mouth the movements of all the organs used in making any sound can be determined with such certainty that deaf-mutes can be, and have been, successfully taught to distinguish these sounds by the eye alone. And it was by such a method that I set out to read the temple inscriptions from the ruins of Palenque, some years ago, at which time I had not heard of Dr. Bell's learned and excellent work. The main feature of those glyphs, by which I was guided, was the outline of the mouth, which the artist had sought to preserve and emphasise at the cost of every other feature, and by this process I found to my satisfaction some ten or twelve sounds or phonetic elements of the speech used by these people; but not knowing the meaning of the sounds in that lost tongue, I did not attempt to verify them, but when I find the time to devote to them I believe I can accomplish that. [Sidenote: TRIP TO AFRICA] It is a part of my purpose, in my trip to Africa, to try to secure photographs of the mouths of the great apes while they are in the act of talking, and to this end I am having constructed an electric trigger, with which to operate my photo-camera at long range, and I shall try to furnish to the eminent author of "Visible Speech" some new and novel subjects for study. CHAPTER XXIV. Some Curious Facts in Vocal Growth--Children and Consonants--Single, Double, and Treble Consonants--Sounds of Birds--Fishes and their Language--Insects and their Language. [Sidenote: SOUNDS UTTERED BY CHILDREN] I shall take occasion here to mention some curious experiments, which have suggested themselves to me in my work with the phonograph. For lack of time and opportunity, I have not carried them far enough to give exact and final results; but it has occurred to me that philology may be aided by taking a record of the sounds made by a number of children daily through a period of two or three years from birth. The few experiments which I have tried in this particular line are sufficient to show that the growth of speech obeys certain laws in the development of vocal power. It is apparent to me that the first sounds uttered by children have no consonants, and that certain consonants always appear in a regular succession and always single. The double consonants develop later, and the triple consonants appear to be the last acquirement. I have not the space to go to great length on this subject, and my experiments have not been sufficient to enable me to formulate with certainty any set of rules by which the development of this faculty is uniformly governed.