By Charles Lennie
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Sample text
Going uphill, a small front and large rear sprocket are selected to reduce the push required from the rider. On the level, a large front and small rear sprocket are used to prevent the rider from having to pedal too fast. Tires absorb some energy Leaf Wheel is fixed to outer race Full aperture Medium aperture Stopped down THE IRIS DIAPHRAGM Cam slot Like the eye, a camera needs a way of controlling light. The eye does this by using the iris (the colored part) to change the size of the pupil at its center.
The filament is coiled and then coiled again, to concentrate its heat and increase efficiency. AN ELECTRIC IMITATION Domestic life was turned upside down between 1900 and 1930. Servants almost disappeared, to be replaced by electrical gadgets of all kinds. It was too much for some people, who wanted their new appliances to look as much like the old ones as possible. So although this early electric heater needs no one to stoke it, it is made to look like an old-fashioned stove. Drill bit suited to wood Lightweight plastic casing High vacuum within bulb Bulb filled with argon gas “Pip” where air was sucked out COMPACT FLUORESCENT LAMP Chuck holds drill bit ELECTRIC DRILL The first portable electric drill was made in 1917.
BRONZE RAZOR This razor was made in about 500 bc, long before mass production. It used a lot of metal, and would have taken a skilled worker many minutes to make. But once made, it would last a long time. Hinged safety cover Plastic dispenser for safe insertion Hose for cooling water When the blade gets dull, the whole razor is thrown away The straight razor is forged from a solid piece of steel Blade edge exposed here Double edged blade Using a straight razor Ejector pins push finished molding out of mold Handle twists to open covers Safety razor Massive metal construction ensures accuracy Disposable razor A CLOSE SHAVE THROUGH THE YEARS Hammer strikes cartridge to make it explode Vanity and convention force most men to shave every day.