We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
MCINTOSH BATTERY AND OPTICAL CO., CHICAGO, ILL., D. S. A. 43 As sunlight is much more powerful than any artificial light, and costs nothing, the advantages of this apparatus are obvious. If sunlight were always available, nothing more would be needed ; but since the investigator, the instructor and the exhibitor will frequently have occasion to use it with artificial light, the inventor has made his Com- bination Stereopticon, so that the optical parts are interchangeable with those of the Solar Apparatus. Ether-oxygen or the oxy-hy- drogen lime light may be employed, and will probably remain the best substitutes for sunlight until considerable advance is made in the production of the electric light in a more economical and con- venient form than at present. OBJECT TEACHING. Teaching by illustation has become an established practice of our day, and no instructor can afford to neglect object teaching. The principal obstacle in the way of its more universal application is pau- city of the school fund, or a failure of the school boaid to realize the necessity for suitable apparatus. It is customary for teachers to ex- temporize apparatus, and in a crude way attempt to aid the eye in making plain many branches of study. This is certainly a help to the pupil in understanding the text book, yet it falls far short of what may be accomplished by suitable aids. In this practical age little value is attached to knowledge that cannot be transformed into capital to achieve some useful purpose, and any measures are certain to be appreciated which not only tend to fix in the memory the dry facts of the arts and sciences, but at the same time reveal their practical appli- cation. As an incentive to study experimental work is of the highest importance. This point cannot be better illustrated than by refer- ence to experiments the writer witnessed when a boy. Having learned “by heart” from a text book on philosophy the properties of matter, none of which produced any deep impression at the time, he chanced to witness the death of a little mouse, which had been placed under the receiver of an air pump, from which the air was exhausted ; also the bursting of a glass flask from the same cause ; and had his hand held by atmospheric pressure on an opening in a glass jar so firmly that he was unable to remove it, until air was allowed to enter the vessel. These experiments made such an impression on his mind that for days he thought of little else, and ever after Philosophy was a new book to him. Many times had he looked at the starry heavens, and had constellations and stars pointed out to him, but it produced only a passing notice. But when he chanced to look through a telescope and beheld the planet Saturn and its rings, astronomy was