196. _What are the usual causes of a child walking in his sleep, and what measures during such times, ought to be adopted to prevent his injuring himself_? A disordered stomach, in a child of nervous temperament, or worms, are usually the causes. The means to be adopted to prevent his throwing himself out of the window, are to have bars to his chamber present, and if that be not practicable, to have either nails or screws driven into the window sash to allow the window to open only for a sufficient space for ventilation, and to have a screw window fastening, in order that he cannot, without difficulty, open the window, to have a trusty person to sleep in his room, who should have directions given not to rouse him from his sleep, but to gently lead him back to his bed, which may frequently be done without awaking him, and to consult a medical man, who will adopt means to destroy the worms, to put his stomach into order, to brace his nerves, and to strengthen his general system. A trip to the coast and sea bathing, in such a case, is often of great service. SECOND DENTITION. 197. _When does a child commence to cut his SECOND set of teeth_? Generally at seven years old. He _begins to cut_ them at about that time: but it should be borne in mind (so wonderful are the works of God) that the _second_ crop of teeth, _in embryo_, is actually bred and formed from the very commencement of his life, _under_ the first tier of teeth, but which remain in abeyance for years, and do not come into play until the _first_ teeth, having done their duty, loosen and fall out, and thus make room for the more numerous, larger, stronger, and more permanent teeth, which latter have to last for the remainder of his existence. The _first_ set is sometimes cut with a great deal of difficulty, and produces various diseases; the _second_, or permanent teeth, come easily, and are unaccompanied with any disorder. The following is the process:--One after another of the _first_ set gradually loosen, and either drop out, or with little pain are readily pulled out; under these, the _second_--the permanent--teeth make their appearance, and fill up the vacant spaces. The fang of the tooth that has dropped out is nearly all absorbed or eaten away, leaving little more than the crown. The _first_ set consists of twenty; the _second_ (including the wise-teeth, which are not, generally cut until after the the age of twenty-seven) consists of thirty-two. I would recommend you to pay particular attention to the teeth of your children; for, besides their being ornamental, their regularity and soundness are of great importance to the present as well as to the future health of your offspring. If there be any irregularity in the appearance of the _second_ set, lose no time in consulting an experienced and respectable dentist. ON DISEASE, ETC. 198. _Do you think it important that I should be made acquainted with the symptoms of the SERIOUS diseases of children_?