_Observations._ 1st. The situation, ventilation, light, and warmth of a school-room, together with the arrangement of the benches, do much to influence the concentration or distraction of the operations of the mind. Let there be attached to the school-house a spacious yard planted with trees; let its architecture be attractive; let the windows be arranged with regularity, and not with the elevation of a convict's cell, and the benches, in every respect, be adapted to the different scholars, so that the position of each may be comfortable, and we mistake if there is not a greater improvement, in a given time, in such a school, than where there is an apparent disregard to the pleasure or comfort of the scholars. -=-=-=-=-=-=-=-=-=-=-=-= 836. What is the effect if the brain concentrates its energies on more than one object at a time? How illustrated? 837. What should be regarded in pursuing any employment? Why? What is said in reference to the arrangement of school-rooms? -=-=-=-=-=-=-=-=-=-=-=-= 2d. Mechanics' shops should receive as much attention, relative to their situation, light, warmth, &c., as school-rooms. If these are duly observed, the nervous influence transmitted from the brain to the muscles will be more stimulating, as well as more abundant; consequently, labor will be performed with less exhaustion. 838. _Repetition is necessary to make a durable impression on the mind._ "The necessity of judicious repetition in mental and moral education, is, in fact, too little adverted to, because the principle which renders it efficacious has not been understood. To induce facility of action in the organs of the mind, practice is as essential as it is in the organs of motion. 839. "In physical education we are aware of the advantages of repetition. We know that if practice in dancing, fencing, skating, and riding, is persevered in for a length of time sufficient to give the muscles the requisite promptitude and harmony of action, the power will be ever afterward retained, although little called into use; whereas, if the muscles have not been duly trained, we may reiterate practice at different intervals, without proportionate advancement. The same principle applies equally to the moral and intellectual powers, because these operate by means of material organs. 840. "According to this principle, it follows, that in learning a language or science, six successive months of application will be more effectual in fixing it in the mind and making it a part of its furniture, than double or treble the time, if the lessons are interrupted by long intervals. Hence it is a great error to begin and study, and then break off, to finish at a later period. The fatigue is thus doubled, and the success greatly diminished. -=-=-=-=-=-=-=-=-=-=-=-= Of mechanics' shops? 838. Is repetition necessary to make a durable impression on the mind? Why? 839. How is it with physical education? 840. What follows, according to this principle?