Tools of Telegraphy Page 4
Page 1- Leg Key, Legless Key, Local Sounder, Mainline Sounder
Page 2- Morse Relay, Bug, KOB, Box Relay
Page 3- Barclay Box Relay, Candlestick Resonator, Swing-arm Resonator, Cordless Jackbox
Page 4- Sideswiper, Repeater, Polar Sounder, Register, Gravity Battery, Insulators
Double-speed Key or "Sideswiper"
This key is commonly called the "sideswiper". It is operated using a horizontal motion. It has two fixed contacts-- one left and one right. The circuit is closed by moving the lever to the right or left. A rocking motion of the wrist and hand was used to send Morse. This was claimed to reduce the problem with "telegrapher's paralysis" as discussed above for the semiautomatic key. Unfortunately the sideswiper is somewhat difficult to operate. It was marketed by Bunnell beginning in 1888, 16 years before the invention of the semi-automatic key. I do not have any information as to the popularity of this key, however, the sideswiper is a relatively scarce device today. This suggests the sideswiper was not popular with telegraphers. The fact that it was not designed to be portable in a manner similar to the bug may have been one of the reasons it was not popular. This one was made by Bunnell, and it includes the spring tension adjustment patented in 1904. It was referred to as the "double-speed key" by Bunnell. It is missing the circuit closer.
The Morse relay was sensitive enough for circuits of two or three hundred miles in length. To extend communications beyond that distance, a repeater was used. A repeater receives weak Morse signals and retransmits the same signals with greatly increased strength. Repeaters are quite complicated due to the requirement of having to send and receive signals in both directions. They usually consist of several specialized relays with multiple magnets and contacts. Many repeater designs were used. The Weiny-Phillips, Milliken, Gheghan, Horton, Neilson, and Toye are examples. This example was made by the Jester-Cooper Company of Houston Texas. It was patented in 1933, making it one of the last Morse repeaters to be designed. This is not the complete repeater system-- at least two other pieces were needed to make a complete repeater.
This is a sounder which has its solenoids magnetically biased by a permanent magnet. This causes it to respond to current flowing in one direction only, thus it is "polarized". This type of sounder was used in line test sets in large telegraph offices. It was not normally used for routine communications. This example is a Western Electric model 7A wound to 1000 ohms.
The "register" was the original Morse receiving device. An electromagnet attracts an armature which causes a stylus to emboss a mark in a paper tape. A weight or spring driven mechanism was used to feed the paper tape through the register. The markings on the tape were then interpreted by an operator. The register continued in general use for only a few years. It was soon discovered that operators could simply right down the message by listening to the clicks of the register. This was called "sound reading". It was actually forbidden by some early telegraph companies, as it was believed to be a haphazard way of receiving Morse. Eventually it was proven to be entirely adequate with regards to accuracy. Sound reading was also found to more cost-effective due to the fact that only one operator was required. The register attendant could be fired ! This register was made by G.M. Phelps for the Western Union Telegraph Company. It has a large clock-spring mechanism and a liquid damper to control the speed of the paper feed.
The gravity battery is actually a form of electrochemical cell used to provide a source of electrical power for the telegraph. By the early 20th century, most telegraph lines were powered by motor-generators, however, the gravity battery continued to be used in way stations to power the local circuit. This practice continued at least into the 1950s. The gravity battery used a zinc and a copper electrode. The zinc electrode is seen hanging from the top of the jar. It is often called a "crow's foot" due to its design. A copper electrode is positioned at the bottom of the jar, and is connected to the circuit with an insulated wire. The term "gravity" is used since the solutions of copper sulphate and zinc sulfate have different densities and seperate like a mixture of oil and water. Solid copper sulfate or "bluestone" is added to the copper electrode at the bottom of the cell. The copper sulfate is slowly depleted in use. More copper sulfate is added to refresh the cell.
Detailed Specifications of the Gravity Battery
While not a tool per se, the development of the glass insulator was critical to the telegraph's success. The original Morse telegraph line constructed from Baltimore to Washington DC used a buried conductor. When it was found that the line suffered from excessive leakage due to faults in the insulation, it was decided to string the wire overhead using wooden poles. The wire was insulated from the pole by sandwiching it between glass plates. Next a glass doorknob was used. The doorknob was mounted on a wood pin, and the telegraph wire was then attached to the doorknob using a small piece of wire. The modern insulator evolved from this arrangement. It was found that even with the wire touching only the glass, excessive leakage or "escapes" were still a problem. This leakage limited the usable length of the line or even prevented its use in wet weather. Improvements in the design of glass insulators reduced the leakage problem significantly, but they never entirely eliminated it. The most important innovation was the "petticoat" design. The petticoat works as a sort of umbrella, and it keeps a dry path from the wire to ground even when the insulator is rained on. Another innovation was the threaded insulator design. Previous to this, insulators were simply pushed onto a wooden spike. Wind combined with the tension of the wire caused the insulator to pop loose from the wooden spike. The addition of the thread prevented the insulator from popping loose, thus greatly improving the reliability of the telegraph line. The insulators shown from left to right are: A.T.&T. Co., Unknown beehive design (probably Canadian), McLaughlin #19, Hemingray #42.
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