Unlike previous questions these are open for discussion now.
With the development of the anchor escapement long pendulums became popular. Some clockmakers stretched the point. This leads to this week's offering.
1. What is a 'Seconds and a quarter' pendulum?
2. What were the advantages and disadvantages of this design.

Joe

Joe,
I think a disadvantage would be that you couldn't have a second hand on the clock. This would have been on a taller clock which normally would have a second hand at that time. An advantage might be a longer running time.

Andy

Hi Andy,
According to the book, that is my source for the questions, some of the clocks had seconds bits. They were marked 5, 10, 15 ect. but had one less mark between them. A 24 tooth escape wheel would make one revolution per minute so it was true at the quarter minute points.

Joe

Sooooo----
The clock runs at 48 beats per minute, 2880 Beats per hour and the simple pendulum length is approximately 1.5316 meters or 60 1/4 inches.(based on 2900 beats per hour. Close enough?) The plot thickens and the post is back to the top of the list.
Dick

Hi All,
The answer to question # 1 is, as Dick pointed out, a second and a quarter pendulum beats at 2880 BPH and is slightly more than 60 inches long.
For question # 2, the apparent advantages are, with 20% fewer beats per hour any pendulum length error is amplified 20% less. Another advantage is that the slower operation contributed to making long running clocks. (Some as long as 3 months)
The disadvantages were, the longer pendulum was affected more by temperature changes than a 1 second pendulum and the rating nut was very near the bottom of the case making adjustments difficult. Some cases were fitted with hinged or sliding doors for access. Joseph Knibb's clocks had the rating assembly at the top and could be accessed by removing the hood.
The first known use of this pendulum is believed to have been around 1675. The maker was thought to be William Clement. Several makers converted 1 second clocks to 1 1/4 seconds. The lenticles in the trunks were filled in and new openings were placed in the base panels.
These pendulums were only around for about 10 years so I guess one could consider them a 'Fad'.

Note: Information for this question was found in 'In Quest of Clocks' by Kenneth Ullyett. Published by Spring Books.

Joe