Douglas Self

The source article linked from the submission mentions electrically synced clocks with the master in the Observatoire.

I don't know why pneumatically synced clocks were preferred. Maybe it was cheaper to integrate the clocks themselves into the system? Patents?

<http://www.douglas-self.com/MUSEUM/COMMS/airclock/airclock.htm>

> At the Paris Observatoire a high-standard astronomical regulator clock was kept running on correct mean time by astronomical transit observations, being corrected daily. Pulses of electricity were sent every second to secondary clocks around the city, the wires being run through ducts in the sewers. Two loops starting and ending at the Observatoire carried thirteen clocks between them, the farthest being at a distance of seven and a half kilometres, or nearly four and a half miles from the observatory. The clocks were of a high standard, so they could keep good time even if the synchronising pulses failed. (The pulses synchronised the clocks but did not drive them, they were weight-driven in the conventional way) The secondary clocks were furnished with second-hands, and were placed so that they could be easily seen from the street, usually in prominent positions. They further distributed time by sending electric signals once an hour to synchronise various public clocks. The system came into operation in 1878.

The website seems to end with a 2015 electric unicycle but not continue on with covering that form factor. Maybe because most people don't refer to those as monowheels anymore.

http://www.douglas-self.com/MUSEUM/TRANSPORT/motorwhl/motorwhl5.htm#air

Also airwheel is kind of a random brand to showcase - Trevor Blackwell made an earlier one https://www.trevorblackwell.com/eunicycle and Solowheel got the majority of the earlier patents (and royalties to this day).

That form factor has come a long way since 2015 though.

Check out this MotoGP style race, they're hitting 50+mph: https://youtu.be/fbX6qaWINBk?si=l2G0JnBxxCMP8a7e

I see them every day whizzing across San Francisco, especially on Van Ness passing all the cars.

I know there's at least two shops in SF selling them, one in Potrero and one in Hayes Valley - https://alienrides.com/collections/electric-unicycles - https://lastmilepev.com/collections/electric-unicycle-euc

Unicycle seems to be the winner. The "wrap around the body" form factor seems doomed from a physics point of view. That big of a diameter has way too much leverage, and the person sitting inside has too little. So you end up doing a flip instead of stopping. As such, their required stopping distances are very long compared to unicycles which can stop as well as a bicycle, if the rider is skilled.

Very off topic, but I have been very interested in Peltier units and Seebeck engines for the last month or so; winter is indeed here. It would be interesting to see these used in a wider scale, or if it is even possible. Here are some links that describe them in more detail:

Thermoelectrical Generator Kit - ThermoGenKit - http://www.youtube.com/watch?v=8mFyiYh94YE

Seebeck Effect - http://www.metacafe.com/watch/1129994/seebeck_effect/

Thermo-Electric Generators - http://www.douglas-self.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm

BMW Heat-Harnessing Technology - http://www.sacarfan.co.za/2009/10/bmw-heat-harnessing-technology/

http://www.innovationsforeveryone.com/Comment_Innovation.aspx?Id=4260

http://en.wikipedia.org/wiki/Thermoelectric_effect

Using both heat and cold you can create a small amount of electricity from these units. I have seen something like this used in a camp. They would place one end of a metal rod into a fire and the other in a bucket of water. Then they could create enough electricity, using some type of thermoelectric circuit, to 'trickle charge' a cell phone or GPS.

This has been around for years. Self's webpage [1] notes that class G amps date back to 1976. They've certainly been used in commercial applications and I'm certain you could buy PCB kits at some point in history.

Apparently, there were a bunch of class G amps that appeared after 5.1 setups got popular, just because of how much less heat they produce per channel.

If you want an efficient, small amplifier these days, class D is also an option. They're cheap, small, and powerful. Much more efficient than class G. If you are just trying to stick a speaker and amp in a musical instrument, I would start by getting an amp that is built into an IC with something that can work with a relatively simple power supply.

[1]: http://www.douglas-self.com/ampins/classg/g.htm

If plethora of designs in search of perfection is an indicator of something of interest, then take a look at the many variations in valve gear design, particularly for locomotives, which needed to operate reasonably efficiently over a wide range of speeds, gradients and loads.

Even more so, consider the many attempts at making non-turbine rotary steam engines, wonderfully documented here: http://douglas-self.com/MUSEUM/POWER/rotaryengines/rotaryeng.htm

My personal favorite is the Tower spherical engine: http://douglas-self.com/MUSEUM/POWER/tower/tower.htm

Unlike most of the designs here, this one was built and even put to a little practical use.

I remember when microphones were physically dangerous. It mentions carbon microphones with the main supply voltage going through them: http://www.douglas-self.com/MUSEUM/COMMS/mechamp/mechamp.htm#tann. But even into the 80s, microphones plugged into portable vacuum tube amps sometimes ended up with the plate voltage (200+ volts) on them and shocked people when they touched them. Stage performers usually brushed a mic quickly with a finger before putting their lips close to it, to make sure it wasn't electrically hot.

I wonder if it resulted in people being more careful what they said near a microphone too.