Subject
- #Precision Engineering
- #H4 Timepiece
- #Horology
- #Navigation Technology
In 1767, the British Royal Society published a detailed technical document on John Harrison's revolutionary marine timekeeper, H4. This document is considered one of the most important publications in the history of marine chronometers. Today, we will examine the innovative technologies of H4 through this document.
Innovative Design for Precise Time Measurement
1. Uniform Power Transmission System
[Fig. 5 - Fusee and Mainspring System]
The most notable feature of H4 is its power transmission method. As shown in the figure above, it was designed to deliver constant force through the first wheel and the fusee. In particular, precise power transmission was possible through the ratchet with 55 teeth and the perpetual ratchet with 75 teeth.
[Fig. 4 - Contrate Wheel and 8-Pin System]
It also implemented a unique remontoire system that automatically winds every 1/8 of a minute using eight pins mounted on the contrate wheel. This is similar in principle to having a small clock that operates every 8 seconds.
2. Temperature Compensation System
[Fig. 12 - Thermometer and Balance System]
One of the biggest problems with clocks at the time was error due to temperature changes. The figure above shows the "thermometer curve" device devised by Harrison. This device, consisting of the upper plate marked AA, the balance marked BB, and the thermometer marked aa, worked as a single system to respond to temperature changes.
3. Innovative Escapement Design
[Fig. 8 - Pallet Detail]
[Fig. 9 - Ratio of Balance and Balance Wheel]
The innovative design of the escapement can be seen in Figs. 8 and 9. Fig. 8's pallet is drawn at 10 times its actual size, showing its detailed structure, and Fig. 9 shows the precise ratio between the balance, balance wheel, and pallet.
Detailed Technology for Increased Accuracy
1. Sophisticated Gear Train Design
[Fig. 3 - Second and Third Wheels]
The gear train of H4 was very precisely designed. The second wheel has 120 teeth and the third wheel has 144 teeth, and each meshes with a pinion of 18 and 16 teeth respectively, delivering precise power.
2. Precise Component Manufacturing Process
Finally, noteworthy is Harrison's innovative heat treatment method. He used an alloy with precisely controlled proportions of lead and pewter. The balance spindles were mixed with pewter and lead at a ratio of 1:12, and the balance spring and pinion were mixed at a ratio of 1:17, and heat-treated at different temperatures.
In Conclusion
Harrison's H4 was not just a simple clock, but a masterpiece that concentrated the best precision machine technology of the 18th century. The drawings examined above clearly show his genius engineering ability and formed the basis of modern precision watchmaking.
This innovative design not only greatly contributed to the advancement of navigation but also had a significant impact on precision mechanical engineering in general. The legacy of H4 continues to be the standard for high-precision machine manufacturing today.
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#Horology #NavigationTechnology #Invention, #IndustrialRevolution, #PrecisionMachinery #History #JohnHarrison
#H4Chronometer #HistoryOfScienceAndTechnology
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