Showing posts with label a. Show all posts
Showing posts with label a. Show all posts

Wednesday, March 18, 2015

Getting a Grip






The colour of a flower is the result of a combination of the floral pigments contained in the petal cells and the optical characteristics of the cells themselves, which is why the colour of flowers in photographs doesn’t always correspond exactly with what the eye sees. The cells walls act like lenses, bending and scattering light rays, producing optical effects that combine with the floral pigment colours to produce unique hues, so even a brick red geranium flower shows a bluish tinge from certain angles (bottom picture). These photos show the cells on the surface of a geranium (Pelargonium) petal, which in surface view look like a patchwork blanket, with the patches stitched together (second picture from bottom x100). A side-on view reveals that each cell is actually shaped like a small hill, and that the ‘stitches’ are really pleats (third picture from bottom x100 and fourth picture from bottom x200). The conical cells are typical of many petal surfaces of flowers visited by insects. So why are they this shape? Their lens-like properties contribute to flower colours but their shape and surface texture seems to have evolved to give the claws of pollinating insects like bees (top picture x100) something to grip. By the clever use of mutant forms of snapdragon that have flat, smooth petal surface cells rather than conical ones, Dr. Beverley Glover at Cambridge University’s Department of Plant Sciences has shown that bees avoid smooth petal surfaces because it’s difficult for their claws to grip them and gain enough purchase to force their tongues into the flower. So ultimately it’s the necessity of giving insects a foothold that has produced petal cells with optical properties that add complexity and subtlety to flower colours. Theres more about Dr. Glovers research in this web site http://news.bbc.co.uk/1/hi/sci/tech/8049954.stm

Read more »

Chinese Kite How to Make a Chinese Kite

How to Make and Fly a Chinese Kite

The Chinese boy is not satisfied with simply holding the end of a kite string and running up and down the block or field trying to raise a heavy paper kite with a half pound of rags for a tail.
He makes a kite as light as possible without any tail which has the peculiar property of being able to move in every direction.
Sometimes an expert can make one of these kites travel across the wind for several hundred feet; in fact, I have seen boys a full block apart bring their kites together and engage in a combat until one of their kites floated away with a broken string, or was punctured by the swift dives of the other, and sent to earth, a wreck.

The Chinese boy makes his kite as follows:

From a sheet of thin but tough tissue paper about 20 in. square, which he folds and cuts along the dotted line, as shown in Fig. 1, he gets a perfectly square kite having all the properties of a good flyer, light and strong. He shapes two pieces of bamboo, one for the backbone and one for the bow. The backbone is flat, 1/4 by 3/32 in. and 18 in. long. This he smears along one side with common boiled rice. Boiled rice is one of the best adhesives for use on paper that can be obtained and the Chinese have used it for centuries while we are just waking up to the fact that it makes fine photo paste. Having placed the backbone in position, paste two triangular pieces of paper over the ends of the stick to prevent tearing. The bow is now bent, and the lugs extending from the sides of the square paper are bent over the ends of the bow and pasted down. If the rice is quite dry or mealy it can be smeared on and will dry almost immediately, therefore no strings are needed to hold the bow bent while the paste dries.

Parts of a Chinese Kite

After the sticks are in position the kite will appear as shown in Fig. 2. The dotted lines show the lugs bent over the ends of the bow and pasted down. Figure 3 shows how the band is put on and how the kite is balanced. This is the most important part and cannot be explained very well. This must be done by experimenting and it is enough to say that the kite must balance perfectly. The string is fastened by a slip-knot to the band and moved back and forth until the kite flies properly, then it is securely fastened.

A reel is next made. Two ends—the bottoms of two small peach baskets will do—are fastened to a dowel stick or broom handle, if nothing better is at hand. These ends are placed about 14 in. apart and strips nailed between them as shown in Fig. 4, and the centers drawn in and bound with a string. The kite string used is generally a heavy packing thread. This is run through a thin flour or rice paste until it is thoroughly coated, then it is run through a quantity of crushed glass. The glass should be beaten up fine and run through a fine sieve to make it about the same as No.2 emery. The particles should be extremely sharp and full of splinters. These particles adhere to the pasted string and when dry are so sharp that it cannot be handled without scratching- the fingers, therefore the kite is flown entirely from the reel. To wind the string upon the reel, all that is necessary is to lay one end of the reel stick in the bend of the left arm and twirl the other end between the fingers of the right hand.

A Chinese boy will be flying a gaily colored little kite from the roof of a house (if it be in one of the large cities where they have flat-roofed houses) and a second boy will appear on the roof of another house perhaps 200 ft. away. Both have large reels full of string, often several hundred yards of it. The first hundred feet or so is glass-covered string, the balance, common packing thread, or glass-covered string. As soon as the second boy has his kite aloft, he begins maneuvering to drive it across the wind and over to the first kite. First, he pays out a large amount of string, then as the kite wobbles to one side with its nose pointing toward the first kite, he tightens his line and commences a steady quick pull. If properly done his kite crosses over to the other and above it. The string is now payed out until the second kite is hanging over the first ones line. The wind now tends to take the second kite back to its parallel and in so doing makes a turn about the first kites string. If the second kite is close enough, the first tries to spear him by swift dives. The second boy in the meantime is see-sawing his string and presently the first kites string is cut and it drifts away.

It is not considered sport to haul the other fellows kite down as might be done and therefore a very interesting battle is often witnessed when the experts clash their kites. —Contributed by S. C. Bunker, Brooklyn, N. Y.

Excerpt from the book:
THE BOY MECHANIC
VOLUME I
700 THINGS FOR BOYS TO DO
WITH 800 ILLUSTRATIONS
1913, BY H. H. WINDSOR CHICAGO
POPULAR MECHANICS CO. PUBLISHERS
Read more »

Tuesday, March 17, 2015

A Pet Named Sneaker

If A Pet Named Sneaker has a traditional feel to it, perhaps its because its author, Joan Heilbroner, penned several easy readers back in the day. Her most famous is the 1962 charmer Robert the Rose Horse (with illustrations by P. D. Eastman).

The hero of her latest book is Sneaker, a snake who can contort himself into seemingly endless shapes. At the storys start, he lives a lonely existence in a pet store until a boy named Pete takes him home. (I applaud the choice of Pete for his name. Beginning readers will learn how adding a final "e" changes the titles "pet" to "Pete.") Sneaker goes everywhere with Pete, including to school, where he learns to read and write, and to the park pool, where he saves a toddler from drowning and ends up as the lifeguards helper.

The story has definite kid appeal and the cartoony illustrations humorously showcase the snakes antics. Id have preferred the story to have been broken into two separate books, one featuring Sneakers adventures in school and the other set at the pool. As is, the transition from school to summer vacation is abrupt. But I doubt kids will mind, and I bet many after reading this book will beg their parents for their own pet snake.

A Pet Named Sneaker
by Joan Heilbroner
illustrations by Pascal Lemaitre
Random House, 48 pages
Published: January 2013
 
Read more »