Babbage’s Difference Engine at Computer History Museum

Today was the last chance to see Babbage’s Difference Engine at the CHM in Mountain View before the owner makes it private again.

The Computer History Museum has certainly matured into a world-class museum over the years.

The docent talked for about 45 minutes. Unfortunately, it was displayed at the end of a hallway. So 100+ people with kids and strollers jostled to get a view.

It’s very impressive in person – consists of 8,000 parts, weighs five tons, and measures 11 feet long, moderately noisy and mesmerizing to watch. The cranker used a moderately strong rowing motion.

Babbage, in building the first computer, did not have the hindsight to start with a smaller version first. Thus he never finished building a working model despite a decade of funding from the British government and the remaining days of his life working on it.

CHM did a fantastic job on the DEC PDP-1 and IBM 1401 display rooms. Only about 50 PDP-1’s were made, so to have a working model is amazing.

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Thomas Inch Dumbbell Links

Thomas Inch was a strongman/circus performer in the early 1900’s.

He is best remembered for creating a series of dumbbells with almost 2.5″ thick handles, the largest weighing 172 pounds (the “Inch”.)

He would demonstrate an Inch lift, then offer a reward to the audience to repeat his lift. Nobody was ever successful, and rarely did the dumbbell even leave the floor.

Although Thomas Inch was very strong, he probably switched weights while on-stage.

Also, the handle had a hole which could be used for cheating by jamming a nail in there to stop rotation, making the lift much easier.

The Inch lift is considered to be a part of strongman, circus or odd lifting.

Another related circus lift was the bent lift, where the body was bent diagonally and one arm was used to press a barbell or dumbbell vertically.

Although a specialist of any size could eventually lift the Inch, successful lifters are most likely grip specialists (COC #3) over 250 pounds with focused training. Non-grip-specialists report that the Inch rolls out of their hands and feels twice as heavy as the actual weight.

Inch Lifts Throughout History

  • press above head/one hand – only a few people (see chart below.) This is the classic lift.
  • deadlift/one hand – Only a few dozen people
  • deadlift/one hand with cans – only a few people
  • carry 2 – only a few people have done a farmers’ walk. Featured at Arnold Classic.
  • press 2 at same time – Mike Burke has bravely lifted 2 above his waist, but failed to press.
Name Year Video Notes
Thomas Inch 1900s   Probably stopped rotation with nail or even switched dumbbells
Bill Kazmaier (WSM), USA 1990 Video Believed to be first to lift 172. “Felt like hitting a golf ball a thousand yards!”
Mark Henry, USA 2002 Video Olympic and Powerlifter
Rich Williams, USA 2011 Video Powerlifter. Thighed and jerked.
Mike Burke, USA 2014 Video Powerlifter

An honorary mention goes to Paul Anderson, the strongest man in recorded history. If he had one, then he would have been able to throw it over his head!

Arthur Saxon was able to do a 300 pound bent lift, so could probably do the Inch also.

Brian Shaw (WSM) works out with the Inch, doing deadlifts and carries.

USAWA: Inch Dumbbell

Joe Roark wrote in 2006:

The hole in the original Inch dumbell (the 172, I mean, Inch had at least four of differing weights, one about 75 lbs) is not all the way through the handle, although the current owner, Kim Wood declined my request to clean out the hole to see how deep it was.

The hole was filled in one night when word got out that Inch's trick was indeed a nail stuck into the hole to prevent rotation- Inch denied this, but rather than prove his point (men were intending to bring nails that night) he had the hole filled in. He had claimed the hole was for escaping gases during the casting- that question put by me to a foundry man elicited a huge laugh. Had he not filled in the hole, he would have been exposed, in my opinion.

These days very strong gripped men by placing a free hand ON TOP of one of the spheres and thus stopping rotation toward the thumb, can get the bell off the floor. Willoughby thought that the narrow handle width -four inches- prevented large handed men from having a chance, but the opposite is true, we now know, because a very wide hand 'wedges' between the spheres and acts as did the nail- to help prevent rotation.

Also, many men can hold the 172 in one hand in the finished deadlift position because the bells rest against the thighs (preventing rotation) so to see a photo of a man holding the bell in this position does not prove to deadlifted it- only that he held it.

I am convinced Inch never cleaned and pressed- or jerked- the Inch 172; indeed he never really claimed he could until others began deadlifting it- then the overhead aspect was mentioned.

It is my view that the 172 was cast probably in 1905 or 1906 - not in the 1800s as is generally thought. On cyberpump's paysite I presented a 22 installment history of the Inch bell and Inch- it is one of two subjects I feel confident enough to call myself an expert. The Inch
W: CoC
yt: Magnus Samuelsson closing Coc #4
Grip Training – Lifting the Inch Replica Dumbbell

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Congratulations on HondaJet USA Certification

Congrats to Honda for earning FAA Production Certification for their first aircraft, the HondaJet HA-420 light business jet.

I’ve been following the news of the HondaJet for over a decade as they progressed step-by-step towards certification.

The HA-420 is the most technologically advanced, fastest (420 knots) and efficient (by up to 20%) small business jet currently certified. Of interest to owner/operators, it may be flown single-pilot.

The price is $4.5 million, which Honda can finance.

The creation of the HondaJet is an epic story, starting with Honda’s founder dreaming of building an airplane several decades ago, and establishing design facilities 2 decades ago in the USA.

A jet engine, the GE Honda HF120, was also certified for this plane.

The total investment to certify both an airframe and an engine must have been staggering to get to this point. Only a multinational mfg. company with support from top executives like Honda can pull that off in peace time.

Even so, aviation is a tough business to make money in, especially as a new entrant.

Japanese companies have a long history of interesting work in aerodynamics. Both the Battleship Yamato and Bullet Train used duck-bill shaped leading airfoils for significant drag reduction. The HondaJet developers likewise use laminar flow nose (see top photo) and wings, and winglets (see second photo.)

According to a review by a friend of Philip Greenspun, the airplane has some issues: interior noise in the passenger compartment is 6 DB too high, only 573 pounds of useful load with full fuel, and a 4000′ runway is needed. Also, a lot of pilot ergonomics that should have made it in, didn’t. Also, the high price is comparable to the the next class up, which are much roomier and have more comfortable useful loads.

yt: Kenny G Live at the HondaJet TC Event with Mr.Fujino,
HondaJet FAA Type Certification Celebration HondaJet Wins FAA Certification
HondaJet Nominated for 2015 Collier Trophy
W: HondaJet HondaJet Pilot Review

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TAP Plastics Mountain View

Although I’ve walked by TAP Plastics on Castro St. in Mountain View a hundred times, today was the first time I went inside.

Their motto “the fantastic plastic place” is accurate.

They have specialized in plastics sales since 1952 and have 21 stores.

  • marketing, signs and displays
  • collectibles displays
  • marine
  • fiberglass laminate supplies
  • custom design (linear, not vacuum forming)

Their web site is a gem, supporting 9 languages using Google Translate.

TAP Plastics Inc.
312 Castro Street
Mountain View, CA 94041

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HOWTO: CentOS 7/Redhat 7 Firewalld Setup for Cassandra Server

How to do initial firewalld configuration for Cassandra Server and Opscenter on CentOS/Redhat 7 with 2 network interfaces, in my case Dell 1950/2950.

First: verify that your network interfaces are associated with a NetworkManager zone:

# grep -i zone /etc/sysconfig/network-scripts/ifcfg-*
# service network restart

Second: add the Cassandra ports to the internal zone (private interface) and public zone (public interface):


# add ports on internal interface for Cassandra server

firewall-cmd --zone=internal --add-port=7000/tcp --add-port=7199/tcp --add-port=9042/tcp --add-port=9160/tcp --add-port=61619-61621/tcp --permanent

# add ports on public interface for Cassandra server

firewall-cmd --zone=public --add-port=80/tcp --add-port=8888/tcp --permanent

firewall-cmd --reload

Edit the files in /etc/firewalld/zones to remove the desktop helper services, then do

service firewalld restart

3. Verify configuration:

firewall-cmd --get-active-zones
firewall-cmd --zone=public --list-ports
firewall-cmd --zone=public --list-services
firewall-cmd --zone=internal --list-ports
firewall-cmd --zone=internal --list-services

Output is:

# firewall-cmd --get-active-zones
interfaces: enp4s0
interfaces: enp8s0

# firewall-cmd --zone=internal --list-ports
7000/tcp 7199/tcp 9042/tcp 9160/tcp 61619-61621/tcp

# firewall-cmd --zone=internal --list-services

# firewall-cmd --zone=public --list-ports
80/tcp 8888/tcp

# firewall-cmd --zone=public --list-services

4. Verify firewall rules with nmap:

# nmap -sS

Starting Nmap 5.51 ( ) at 2015-10-15 22:34 PDT
Nmap scan report for
Host is up (0.075s latency).
Not shown: 997 filtered ports
22/tcp open ssh
80/tcp open http
8888/tcp open opscenter

Nice! :)


As always, if you experience network issues on linux, disable selinux, firewalld and TCP wrappers first and verify if those are the source of the problem:

setenforce 0
service firewalld stop
cat /etc/hosts.*

Fedora introduces Network Zones Network Zones

Posted in Cassandra, Linux, Open Source, Storage, Tech | Leave a comment