THE WONDERS OF GLASS

Wanganui Chronicle, Volume 83, Issue 47, 25 February 1939, Page 12

THE WONDERS OF GLASS

Nobody knows who first discovered that certain shaped pieces of glass would magnify objects to many times their real size, but the fact has been known for very many centuries, probably ever since glass was manufactured. If you have ever looked through a bottle of clear liquid at a newspaper or a book you will have noticed that the print is made much larger, and as practically any curved glass will magnify things in the same way, this quality was no doubt discovered quite early, and known t o most people. It was quite interesting, but there didn’s seem much point in knowing about magnifying glasses—not until clever men began to think how they could use them to advantage.

ine nrsi use io wnicn tney were put was as a help to people with failing eyesight —as spectacles, in fact. And. from the thirteenth century onwards, it was no uncommon sight to see people, particularly elderly people, with spectacles perched on nose. Then, in the seventeenth century, an Italian scientist. Galileo, began to experiment with microscopes, which are actually only instruments for magnifying small objects, and succeeded in making a satisfactory one. About fifty years later another scientist. Robert Hooke, made lenses with threads of spun glass fused together. He did not stop short at making his microscope though; he turned it to practical use. and with it studied insects and plants. Once he put a piece of cork beneath the microscope and discovered it was made of “little boxes of cells.” He did not realise the full meaning of this, though, for in those days no one knew what scientists were to discover later, that all things are made of tiny groups of cells, or “boxes.” Another Italian. Malphigi, took a hand in the work on microscopes, and he also studied animals, insects and plants. During the course of his work he discovered the pores in leaves and the breathing tubes of insects. A Dutchman, Jan Swammerdam, conducted similar experiments, and found the red cells in the hlooci of a frog. All these men were contributing to the welfare of humanity, though it is quite probable that they did not realise the importance of their work. It was only when the microscope discovered the hidden secrets of Natures wonderful mechanisms and the tiny organisms that are everywhere, in every substance, that science could help the sick, discover the cause of and the cure for diseases, and learn about the way that all things live and die. These men. with their rough, inefficient microscopes, were making the first steps towards a new and wonderful era of discovery.

’n the middle of the seventeenth century another Dutchman. Antony van Leeuwenhoek, set himself to

work making better lenses for microscopes, for the inefficiency of the type then in use irked him, as indeed it did all men eager to discover more and more about the wonderful life they found in seemingly inanimate things. He made the grinding of lenses a tine art, and greatly improved the efficiency of the microscope. With this new, powerful ally he did much valuable experimental work. He was probably the first man in the world to see bacteria, and to watch blood circulating in living tis-

The next improvement came with double - lensed microscopes. Two Dutchmen. Zacharias and Johann Janssen, were the first to use a double lens. One of the brother's sons was playing with two lenses, one concave, the other convex, when he put both of them together !n front of an eye. He looked through them, thens creamed in terror, and when his father came running out, explained that he was frightened because the weather vane on the church spire had jumped nearer to him. The father, who was a spectacle maker, put the lenses in front of his own eye, and realised that here was a magnifying glass such as had never been used before. He made the first telescope by fixing the two lenses to a board. When Galileo heard of this discovery he also experimented with double lenses, and made a really efficient telescope by putting them into a tube. With his telescope he found the mountains on the moon, and made other astronomical discoveries.

This double lens magnifying glass was a wonderful improvement on the single lens, but there were so many optical difficulties to overcome that it was not until the nineteenth century that an efficient microscope could be made with a double lens. To-day the double microscope is one of the most perfect and efficient instruments In the world, magnifying objects to four and five thousand times their normal siz®