More Counterfeit Stuff from China

The Association of Diving Contractors International has alerted the industry to counterfeit diving helmets. Copies of the well known Kirby-Morgan helmets are being sold and advertised as being "interchangeable" with the brand name helmet. See this link for the press release from Kirby-Morgan. Use of the counterfeit helmet could have deadly consequences. While this will only be of interest to the professional diver, some technical divers may use this equipment and should be on the lookout for it.

Red Dog at the Waterworks Museum

Grandpa took D and I to the Metropolitan Waterworks Museum in Boston. It is a pumping station that pumps water from the reservoir across the street to a reservoir at a higher elevation so that water can flow by gravity to the City of Boston. It was built before 1900 and remained in operation until 1976. If you like old steam engines, this museum has three of them that drove big reciprocating pumps. This is a picture of me next to the mechanism that operated the steam valves on the Worthington-Snow horizontal engine.

The other two engines are big vertical engines that are three stories high. If you are in Boston, the museum is easy to get to. Take the "C" branch of the Green Line to Cleveland Circle (end of line) and then walk straight ahead for 1/2 mile. And best of all, the museum is free.

Rule 303

When my weight hit the caliber of an Enfield rifle, I knew I had to do something if for no other reason than to reduce wear and tear on my stainless steel knee. I found a program that several relatives had success with and got on it. It's basically a very low (almost non existant) sugar and carbo diet. Anyway, it's working and I have lost two stones with another 2 stone or so to go.

Red Dog at the Museum of Science

Grandpa took me and the boys to the Boston Museum of Science. While we were there we went to the electrical show. They have the worlds largest air insulated Van de Graaff generator and every hour they turn it on and send lightening bolts arcing through the air. At one point, they had a cute girl get into a Faraday Cage and then they shot lightening bolts at her. But she was perfectly safe. 

Slide Rules

We took our grandsons to visit the MIT Museum on our recent vacation. It seems the museum had a display of slide rules and I took the opportunity to teach the boys about an instrument that was now obsolete.

Slide rules make use of logarithms. When working with logarithms, the log of the product of two numbers is equal to the sum of the logs of each number. When Napier invented logarithms in the 1600s this rule was used to simplify arithmetic because the multiplication of large numbers could now be reduced to simple addition. I don't think they teach logarithms any more. Slide rules are just logarithmic scales inscribed on a ruler. You multiply and divide by adding or subtracting lengths on the ruler.

As an engineering student, my slide rule was my constant companion. Indeed, it was one way to identify who was an engineering student. Mine served me well through graduate school in 1974. At that time, calculators were making their way onto the market but they were very, very expensive. For a while, there was a controversy about allowing students to use calculators as it may give them an advantage over poorer students who could not afford one. That didn't last long as soon calculators became cheap.

Lots of stuff was designed and built using slide rules. The scale forced you to think about the accuracy of your calculation as the scale would get cramped in numbers above 5 and you couldn't carry too many decimal places. The term "slide rule accuracy" was a common benchmark. Today, an engineer can calculate out to 6 decimal places but it doesn't mean that his answer is any better than the guy with the slide rule. It also forced you to use scientific notation in order to keep track of the decimal place. A common multiple guess test trick was to provide answers differing only by a factor of 10 to see how well you managed the decimal point.

Slide rules are no longer manufactured. K&E, who made most of them, retired their dies and donated them to the MIT Museum. Knowing how to use them is a useful skill.

Book Review - Light of the World

Dave and Clete and their families, including Alafair and Gretchen (Cletes daughter), are vacationing in Montana. But, as you can guess, bad stuff follows them. Alafair sees a serial killer that she interviewed in prison several years ago. He was not happy with what she wrote about him and is seeking revenge. Also, a teenage girl who had been adopted by a local wealthy family turns up dead and is soon followed by a couple of corrupt local cops. It's hard to imagine a small town in Montana attaining shuch a high body count. Dave and Clete hit the problems in their typical head on style that eventually ends in a fire fight in the mountains. This book takes off from the first page and keeps you interested. Yes, Burke does spend a few paragraphs preaching about the devastation that fracking is visiting on the coutryside, but if you ignore his environmental rants, its a good read.

Head Count

Saudi Arabia beheaded two armed robbers and a murderer for a monthly count of three. It's probably low because of Ramadan. This brings their year to date total to 53. I apologize for the late post. I was on vacation and just got back.