Calculating the standard deviation

1. Put the scores in order down the page.
2. Work out the mean.
3. Now calculate how much each deviates from the mean.
4. Now square each of these deviations.
5. Add them all up.
6. Now divide by the number of scores.
7. Lastly find the square root.
8. This is the standard deviation.

Mouth-to-mouth artificial respiration

In certain accidents, if breathing stops, it is possible to save life by artificial respiration. This means that someone else causes air to enter and leave a person’s lungs. The method of artificial respiration now recommended by the U.S. Army, the Red Cross, and the Boy Scouts of America is a method of mouth-to-mouth breathing. First, place the victim face up. Tilt the victim’s head back so that the chin is pointing upward. Next, if there is any foreign matter in the victim’s mouth, wipe it out quickly with your fingers. Then, with your right-hand thumb, pull the jaw down to clear the tongue from the air passage in the back of the victim’s mouth. With your left hand, pinch the nostrils to prevent the air you blow into the victim’s mouth from escaping through the nose. Now, place your mouth tightly over the victim’s and blow into his or her mouth until you see the chest rise. Remove your mouth, turn your head to the side, and listen to the outrush of air that indicates air exchange. Repeat blowing. For an adult, blow vigorously at a rate of about twelve breaths a minute. For a young child, take relatively shallow breaths, at a rate of about twenty a minute.

Creating a new Web page

You don’t need any special tools to create a Web page. You can use any word processor, even WordPad or SimpleText, which are included with the basic Windows and Macintosh system software.

To create a new Web page:

1. Open a text editor or word processor.
2. Choose File > New to create a new, blank document.
3. Create the HTML content as explained in the rest of this book.
4. Choose File > Save As.
5. In the dialog box that appears, choose Text Only (or ASCII) for the format.
6. Give the document the .htm or html extension.
7. Choose the folder in which to save the Web page.
8. Click Save.

Printing black and white photographs

1. Chemical solutions should be prepared and arranged in three dishes in the order in which they will be used – developer, stop bath and fix. They must be brought down or raised to the correct temperature (about 20°C) and there should be enough of each to give a depth of 5cm.
2. The film should be cut into strips so that all will fit on to a single sheet of 10 x 8in paper. Clean the negatives and the sheet of glass with an anti-static cloth. Then switch off the white light and switch on the safelight.
3. The enlarger is a convenient light source. The height of the head should be adjusted so that its beam illuminates an area slightly larger than the sheet of glass being used. Stop down to f8 and cover the lens with the safe filter.
4. Take a sheet of printing paper and lay it, emulsion (glossy) side up, in position under the enlarger. It will not, of course, be affected by the filtered light from the enlarger. Lay the negatives, emulsion (matt) side down, on top of the paper and cover them with the sheet of glass to hold them in place.
5. Switch off the enlarger and then move the safe filter away from the lens. Switch on the enlarger again and expose the paper for 10 seconds. This should be accurate to within about one second.
6. The exposed photographic paper should now be taken from under the glass and slid into the developer dish, emulsion side up.
7. When the paper has been in the developer for about 30 seconds the image should begin to appear and it will continue to darken for about two minutes. Agitate the paper gently during this period by rocking the dish or moving the paper about carefully with the tongs.
8. After the prescribed time the image reaches a stage where there is little further change in its density. At this point, remove the sheet from the developer and let the liquid drain off.
9. When the developer solution has drained off the paper, take the second pair of tongs and transfer it to the stop for 15-30 seconds.
10. Transfer the print from the stop bath to the fixer. After about a minute the white light may be switched on and the print can be examined.
11. The print should now be transferred to the wash and kept there face down for 30 minutes, or at least twice as long for double-weight paper. In the case of resin-coated paper it need only be for five minutes.
12. The finished print should now be dried. If a squeegee roller or photographic blotting paper is used to remove excess water care should be taken not to get dust on to the surface, which will remain tacky until the print is dry.

HOW TO MAKE A KITE

TWO-STICK SQUARE KITE

Frame. No matter what size, you’ll need two strips of wood the same length. A lightweight wood like pine, spruce, or split bamboo is best. For kites more than 1 metre in length, use wood 1 cm. wide. For smaller kites, use 75 mm wood. First, notch both ends of each piece to a depth of about a quarter of an inch. Next find the center of each piece, position the two at right angles, and glue. When the glue is dry, lash the pieces together with fishing line or heavy thread and spread a thin coat of glue over the lashing. (Don’t fasten with nails, tacks, or staples, since they add weight and weaken the wood.) Then string lightweight cord or fishing line through the notches so that the resulting frame is taut.

Cover. Use newsprint for smaller kites and brown wrapping paper or any paper about the same weight for larger ones. If the paper is wrinkled, it should be ironed. Next, outline the frame on the paper, leaving an extra inch all the way around. If the cover is to be decorated, this is the time to do it. Use crayon, water colors, or glue-on cutouts. Then glue the cover to the frame, bending the extra inch around the string and leaving room for the crosspieces to protrude. The cover should be tight and flat. After it is in place, apply a light coating of shellac or dope.

Controls. The kite’s controls are the bridle, which is used for steering, and the tail, which helps keep the kite upright. For the bridle, use two lengths of string, each about a quarter again as long as one of the supports. One piece is fastened a few inches from each end of the horizontal support, and the other is attached in the same way to the vertical support. The flying line, for which you’ll need at least 100 metres of wrapping twine, is fastened where the strings meet. For the tail, start with 5 metres of string; more, if the kite is a large one. Attach strips of rag at 25-or 50-cm intervals; then fasten the tail at a point 10or 15 cm above the base of the kite. Determining the proper length for the tail is a matter of trial and error. If the kite dives, haul it in and add more. When the tail is right, the kite will remain on an even keel.