A new metal and new possibilities 


Мы поможем в написании ваших работ!



ЗНАЕТЕ ЛИ ВЫ?

A new metal and new possibilities



For some time past engineers have been trying to make titanium practicable. It now seems they have succeeded in making production possible on a more or less large scale. Tita­nium is a new metal, one of those sensational new finds, like penicilline, nylon, plastic etc., which have revolutionalized our lives since the war. Titanium is a material possessing such exceptional properties, that we may rightly speak of a wonderful metal. Although being a metal, titanium can be applied in many more cases than only in the manufacture of the machine parts and the like, for which metals are commonly used. It is claimed to be able to increase the whiteness of white paint, to improve certain kinds of cosmetics, to make window panels transparent, to strengthen silk and to serve hundreds of other purposes.

Still it will probably be as a metal that titanium will enter upon its victorious way into the history of mankind.

In the first place this metal is much lighter than e. g. iron (although it is about 67% heavier than aluminium, it is more abundantly available) and yet of a very considerable strength. Furthermore it will resist the corrosive action of sea-water. By adopting-titanium it will be possible to provide ships hulls with a non-corroding covering with greatly reduced maintenance cost as a result.

Many problems in the construction of jet engines will be more readily solved, and- bridges, steel window frames, lifting cranes and other machinery will be given a much longer life. That in all these cases a very considerable saving in weight will be effected, is evident.

THE HUMAN MACHINE

Since man's muscles are his simplest form of power, they were the first source he relied on. The chief limitation to muscle power is obvious: a muscle can exert force only over a limited distance. Furthermore, a man cannot use his muscles continuously: he needs rest. For thousands of years man knew no other source of power. A11 he could do to make work easier for himself was either to force other men to work for him or to devise tools.

In ancient times men supplemented their limited power by making use of slaves. All the great buildings and temples of ancient civilizations were built by slave labor. But the cost in human effort (and suffering) can be judged by comparing slave labor with the power that we use in modern technology. Assuming, that everyone, in the United States commands the energy equal to 10 tons of coal a year, it is as if every American has 100 slaves to work for him.

In order to make the most of their slaves, however, the ancients did what they could to make the heaviest work possible. Heavy materials were hauled on sledges to reduce friction, and water or mud was used as a lubricant. Another labor-saving way of moving heavy stones, was by means of rafts towed along rivers. Rocks or stones that were too heavy to be lifted directly were often dragged up a slope of earth; then, after the blocks were in position, the slope would be removed. Much of the material for the great pyramids of Egypt was handled in such ways. Levers, pulleys, and rollers also enabled men to use their muscles to greater effect.

Why did not early civilizations make more use of animals to help with the heavy work. The answer to that question is that until about A. D. 1000 men were so ignorant of animal anatomy that the harnesses they made allowed the beasts to exert only a small fraction of their muscle power.

Thus, the human machine remained the only universal source of power until the last years of the Roman. Empire — about A. D. 500.From that time on, a shortage of slave labor in Europe and Asia Minor forced men to search for — and to find — other sources. Even today, though, in countries that are technologically undeveloped, the widespread use of manpower is still common.



Поделиться:


Последнее изменение этой страницы: 2017-02-09; просмотров: 373; Нарушение авторского права страницы; Мы поможем в написании вашей работы!

infopedia.su Все материалы представленные на сайте исключительно с целью ознакомления читателями и не преследуют коммерческих целей или нарушение авторских прав. Обратная связь - 18.212.87.137 (0.019 с.)