Open main menu

Page:Popular Science Monthly Volume 89.djvu/473

This page needs to be proofread.


Popular Science Monthly

��459

��A Convenient

A STURDY shoe rack can be constructed as fol- lows ; Fasten a board along the wall , or if preferred, on tlic door of the bedroom closet, and then attach a metal strip as shown. The metal support may be of tin or sheet-iron, but if made of brass and nickeled it will have a rriuch better appearance. The shoes are hung by the heels . — Geo. W. Greene.

��An Exceedingly Sim- ple Arrangement for Keeping Your Shoes Out of the Way

��Shoe-Rack

���How to Calculate Distances

IT is often necessary to measure ap- proximate distances from one object to another quickly, as in photographing with a Kodak. An instrument that enables one to make such measurements can readily be made, using the angle of incidence as the principle upon which to work. Such a device, made according to the description, is simple and compact. It can be constructed either of hard- wood, or sheet metal, cut to the size and shape shown in the illustration. Running along the top of the device is a sight tube, consisting of a small metal tube soldered or securely fastened with wire. A le\'el, in the form of a metal hand, is fastened as shown, the hand being left free to swing back and forth along the face of the instrument.

The device is now complete, except for the markings, which arc deter- mined as follows: Selecting a lc\-el ground, a distance of loo feet is measured off. Standing at one end of the measured distance, sight through the tube to the

���The Angle of In

cidence Is the Foun

dation Principle

��base of an object placed at the other end of the measured distance. By base is meant the base line, or point of meeting between the ground and object. After carefully sighting in this manner, at the same time allowing the hand to swing free, the hand is now caught under a finger and pressed against the face of the instrument, to prevent further move m e n t. A mark is now made at the point of the hand, and this in- dicates loo feet in future measure- ments.

The other dis- tances are measur- ed in the same manner, care being taken always to be on a level ground; the measuring of the short distances can be done in- doors very conveniently. Obviously, the nearer an object is to the observer, the more the instrument must be tilted to sight at the base line of an object, and vice versa. Therefore, to make accurate measurements of distances, the instru- ment must always be used by a person standing up straight, and one of the same height as the one who made the mark- ings, for they would not be absolutely correct for anyone of different height. If extreme compactness is not a requirement, the instrument can be fastened to a rod, with a pivot, and this pressed into the earth to form a support, thus allowing it to be used by anyone. The object sighted at should always be on a le\'el with the observer, in order that the proper distance be- tween the two may be found. Such a device is especially valuable to the amateur photographer in determining the dis- tance between his camera and the object to be photographed, and will greatly reduce the number of failures due to incorrect judging of distances.

�� �