Science and Industry

on the World today


April 1957

AUTOMOTIVE engineers disagree sharply on just what is the host kind of suspension system. Hence they are keeping a sharp eye on the performance of the novel air springs of the 1957 Cadillac Eldorado Brougham. Cadillac claims that this pneumatic suspension system, the first used on passenger cars, offers a lot of advantages including notably superior riding qualities under every sort of condition. With Packard and Chrysler backing the rival torsion-bar suspension system, an engineering battle is on.

The principle of the Eldorado air-spring system is simple. When a bump pushes the wheel up against the car, the shock is absorbed by a cushion of compressed air, instead of by bending strips of steel, as with conventional leaf springs, or by twisting a steel rod, as in the torsion-bar type. The idea itself is not new: a patent was granted for improved air springs as far back as 1847; they were developed experimentally for motor vehicles in the mid-thirties and have been used successfully in recent years on buses, truck trailers, and experimental trains.

The Eldorado has a suspension system for each wheel. When a wheel jounces, a piston pushes against air in a domed chamber. The chamber is connected to an air reservoir and pump, which adjusts the pressure to meet varying conditions.

If there should be a slight air leak, or changing temperature should reduce the pressure, the pump will raise the pressure again. If the car is not exactly level, or if a heavy load pushes the body down on the springs, the system automatically adjusts the air pressure to level the chassis or bring it up to the proper height. A built-in time delay keeps the pump reacting to each bump. When the car doors are opened, this time delay is cut out, so that the height adjustment is made instantly as people enter or leave the car.

Leveling and constant height are of course particularly important for truck trailers that carry a wide range of loads. Cadillac claims that the device has several advantages for passenger cars as well. For one thing, it gives full travel to the suspension system even under the heaviest load, so that you don’t “hit bottom" on a bad bump. At the same time, because the distance from wheel to frame is constant, engineers can design the underpinning of the car for best performance, instead of having to compromise to achieve average performance under a variety of loads.

Riding on air

Cadillac’s engineers declare that the air cushion improves the ride by dampening the spring motion and at the same time reducing the strain on shock absorbers. And since air oilers gradually increasing resistance ns it is compressed, the air cushion gives a soft ride over the little bumps of a smooth road and resists major shocks. This effect is increased by the ingenious design of the piston and air dome, which increases the area under pressure as the piston moves upward.

Crities of air suspension center their doubts on such points as the difficulty of preventing leaks, the tendency of the air in the system to change volume, the cost of the equipment, and the space required for the pump-reservoir systems.

Torsion-bar advocates say that their system can be adapted to do everything air suspension does and provide some additional advantages as well. If the next few years see air springs adapted for moderately priced cars, the average car owner will have plenty of opportunity to judge for himself which system comes closest to giving him that magic-carpet ride he’s been waiting for.

Power nailers

Drilling and sawing have long since been taken over by power tools. Until recently, however, nailing still had to be done the way it had been done for millennia — banging away by hand with a hammer. The expense of the 50 to 100 thousand nails used in an average house is not in the nails themselves but in the man-hours it takes to drive them -at something over $3 an hour on the average.

Now, however, two new power nailers claim to reduce that cost considerably. Roth work with compressed air. In both the nails are carried in hoppers and are automatically fed through a hose to the nose of the machine when it is pushed down against the spot where the nail is to be driven.

Nail-A-Matic, made by United Shoe Machinery, is an oscillating hammer that hits the nail head 70 times per second. It handles nails from 2d to 16d, drives them flush or countersunk, or leaves them extended. The Morgan Nail Driver, made by Morgan Machine Company, is a single-blow nailer that drives up to sixty 4d to 8d nails a minute. Nose adapters permit nail driving at almost any angle. These are no tools for the do-it-yoursell shoppers, however. They cost about $1000 apiece.

Isotope prospecting

Variations in the relative frequency of two kinds of oxygen atoms may make possible a new type of prospecting for valuable ores. Experts say that the method, developed by California Institute of Technology geologists and geochemists, may prove to be one of the most significant contributions to prospecting of the past fifty years. At the same time the new technique will help scientists learn how the earth’s crust was formed.

Today, most surface ores in the United States are already being worked, and discovery of underground ores is pretty much a matter of luck. Instead of gradually tapering off, a deposit ends with a sharp boundary, so there are no scattered traces to lead to the main body of ore.

There is one clue, but until the development of this new technique it wasn’t particularly helpful. The ore was deposited millions of years ago when hot fluids forced themselves into previously existing rock formations. The heat of this process changed the chemical composition of the surrounding rock. Unfortunately this changed area, called an alteration halo, is uniform in chemical composition and texture throughout, so there is no way to tell in what direction the ore deposit lies. Since the alteration halo can be from 10 to 1000 times the size of the deposit, finding the ore was pretty much like finding’a needle in a haystack.

Now, scientists have found a clue locked in the halo rocks. Uniform in every other way, the rocks vary in one thing. The oxygon in rocks is composed of several different oxygen isotopes — that is to say, oxygen atoms that are chemically alike but differ in the number of neutrons in the atomic nucleus. In ordinary rock, the isotopes are scattered in uniform proportions. In the halo rocks, however, the heat has altered this isotope ratio. As you approach the ore deposit, the ratio between oxygen18 — an oxygen atom with ten neutrons — and oxygen16 — with eight neutrons — changes in direct proportion to the distance from the ore mass. By checking this isotope gradient, the prospector can tell whether he’s getting hotter or colder.

To discover this isotope difference, the Caltech scientists used a special mass spectrometer originally developed at the University of Chicago. Mass spectrometers work by ionizing atoms, passing them through a magnetic field, and then measuring the amount the field deflects them. Since this depends on the mass of the atom, it is possible in this way to detect very small differences in atomic mass and thus to distinguish one isotope from another. The device used at Caltech was so precise that it could detect the addition of a single unit of oxygen18 in 2 million units of ordinary oxygen.

Oxygen isotope ratios are also expected to reveal much about how the earth’s crusts were formed, since they will give clues to the temperature of the rocks millions of years ago. They are already proving useful in determining what the temperatures were many years ago in Arctic and Antarctic regions. It is believed that the ratio of O18 to O16 in the oxygen in rain or snow is directly proportional to the temperature at the time the rain or snow falls. Scientists digging into the Greenland Ice Sheet use the isotope ratios to determine annual variation of temperatures and to identify the layer of snow accumulated each year.

Tunnel to nowhere

The problem of how to get rid of atomic debris is forcing engineers to devise all sorts of expensive expedients. Under the Hanford atomic plant at Richland, Washington, for example, there is a tunnel 500 feet long that contains what may well be the shortest full-scale railroad in the world.

When worn-out plant equipment is too rad inactively “hot" to be repaired and too heavy to be easily moved, it is loaded onto a flatcar and rolled into the tunnel. When the car stops, a concrete, water-filled radiation barrier gate clangs shut, safely sealing off the contaminated equipment underground. The tunnel will hold twelve loaded flatcars. Less heavy equipment that becomescontaminated and worn-out is crated and hauled to a desert burial site.

The magic duplicator

Closed-circuit television and electrostatic printing have been teamed up to produce an office duplicator for the age of automat ion. No preliminary work is required — no need to make a plate or stencil, type a sheet, or set type — you just stick the original into the machine. Not only can one original be copied simultaneously on any number of printers, but the printers can be scattered miles from the original and from one another. Each of the printers spins out three copies a second.

The device consists of a transmitter and receiver-printers. The transmitter’s pick-up unit works in principle very much like a TV camera. A tiny spot of light, only .006 inch in diameter, sweeps across the copy 5100 t imes a second — fast enough to cover three 8 by 11 ½ inch sheets in that time.

The light reflected by the scanning beam is picked up by phototubes, which emit an electron flow proportional to the amount of light reflected. Thus the flow varies sharply according to whether the beam is hitting dark ink or light paper. This electronic signal is transmitted to the printer unit.

The printers can be next to the transmitter or anywhere along a closed TV circuit. At each receiver the signal is amplified and applied to the grid of a cathode-ray tube. The grid receives a greater positive charge at each point where the scanning beam has hit a dark spot—part of a letter or line on the original. These charges on the grid are reproduced on a facing sheet of copy paper in a pattern that matches the pattern of lines or characters on the original copy.

The copy paper is then automatically pulled away from the tube face and dusted with black powder — the “ink.” The powder clings to the paper only where there is a positive charge, leaving it blank elsewhere. When the dust pattern is heated and pressed into the paper, it forms a permanent imprint that matches the original.

Stanford Research Institute is developing the system for A. B. Dick, manufacturer of duplicating equipment. At the present stage, the device prints text from 35 mm. film onto paper tape, but it is being adapted to paper in standard office sizes. The researchers hope to make the machine even faster, and to improve it so that it can reproduce photographs as well as type and line drawings.

The Brenthophone

Hearing aids have been adapted as a tool of the anesthesiologist. The small size and light weight of the transistor type have led to its use in keeping tabs on the breathing of unconscious patients undergoing surgery.

Ordinarily, the only way to check on inaudible breathing is to watch a rubber breathing bag as it rises and falls. This gives no warning when the patient’s breathing is partially blocked, however —and besides, the moving bag tends to hypnotize the observer.

With a hearing aid the doctor can tell exactly what is happening by listening rather than watching. The aid is taken apart and its microphone put in a cork. The cork is inserted into a small T-tubc, which is placed anywhere in the anesthesia breathing circuit. The smallest breath moves the air in the T-tube and the noise is picked up by the microphone. The earphone may be worn by the doctor or placed in a paper cup that acts as a loudspeaker, making the sound audible to everyone in the operating room.

The Breathophone was developed by a doctor and a dentist at Lutheran Hospital in Baltimore. It is especially valuable in head and neck surgery.