An Article In Meteorite Times Magazine
by Jim Tobin

Weighty Matters

A good day at the swap meet is a one scale day. But, today I had a two scale day and they were really nice ones. I have for a number of years been collecting and slowly upgrading my scales. I have had NASA surplus very recent ones and older one out of industrial environments, antique ones, complicated and simple ones. I have kept some and sold some it is similar to collecting meteorites. If you have two and limited space it May be better to sell one and upgrade. Among my favorites are always Mettlers. They are just too cool for words once you take off the case and look inside.

I have been using a Sartorius Kilomax for measurements in the 160 - 1000 gram range. Today I accuired a really nice Mettler 1200 that works better and tops out at 1200 grams. So I will probably be moving out the Sartorius in a couple months at a swap meet I sell at each year.

I have only had one scale in all the years that I could not get running accurately. That is a 10 kilograms capacity Mettler. Usually it is something fairly simple if they need any work at all. That one however did have a couple broken parts and since it is fairly old I wonder if I can even get the parts. You never get manuals or parts lists. And today was the first time I have ever gotten an original plastic cover for one.

The joy of older Mettlers is that they have precision weight sets inside. This feature makes it unnecessary to have a set of calibrated brass weights that you move around on the pans till they balance. As you turn the knobs on the scale in each of the ranges fingers inside lift the ring weights and apply the weight to the end of the beam. When the lifted ring weights matches the specimen weight you read the figure on the front panel. It is a little more complicated than that because the fractional gram amounts are projected as an image created by a ray of light passing through an engraved glass on the extreme opposite end of the balance beam. The beam itself is a complex system of jeweled bearing surfaces some knife edges and some frictionless support points. The balance beam is damped by a disk baffle that moves in a closed cylinder. Without damping of some kind you would grow old waiting for the beam to stop moving. The technology of it is just fascinating to me.

The other scale I got today is a Mettler H54AR it is the one with a plastic cover. One of a long line of scales in the nothing to 160 grams range that were produced for years. I have two others of the weight range that are far older then the one I got today. Today‘s acquisition is however, actually 28 years past its last calibration date. That is if you believe the sticker on it. Usually that is a reliable bit of evidence for when the scale was removed from active use at a lab or other facility. Fortunately, there are procedures that can be done to test and verify the accuracy of mechanical scales. Calibration procedures that are fairly standard from one model to another can be run to bring the machine back into accuracy. Sometimes the movement is sticky that can be a real nuisance. You end up tapping lightly on the side of the scale to get it to focus. I have been using one that is a little sticky for a while. Mainly because I really like the scale. But I think it is time to move it to a shelf on display. The H54AR will be my working scale for the near future. After all, it is made to read to .00001 grams accuracy. Though I would never list the weight I got in a real world situation to that many figures. It is kind of neat to know that I can weigh really tiny things. In past articles I have weighed individual chondrules and spheroids from Meteor Crater. But, what is never seen by the reader of those weights is how really far the lighted numbers roll on the screen before stopping. It is not like a triple beam scale or electronic scale. You really get to experience the degree of change from zero that tiny object make on the scale. When it comes right down to it we are working in meteorites with very small bits of primordial material. Crystals and chondrules and grains of nickel iron. They are packed together into larger rocks sometimes, yet it seems we always return to looking at the individual components before it is over.


 


I guess I have one advantage over most meteorite collectors, I will have one of the most accurately weighed collections in the world if I ever get around to making all the measurements.

There was a time in the past before all the NWA meteorites appeared on the scene that collectors had a small group of meteorites to buy at any one time. There were fewer dealers and each would have a selection of specimens that might change only a couple times a year. It could be a long time till a meteorite you wanted became available. It was a more patient and slower paced collecting environment. We learned more I think about the meteorites and cared perhaps a little more about them. I remember times when there were no ureilites and aubrites and howardites, that is except the one the class was named for. There were no lunars and only a couple martians later on. Today , we have many of every class available, the prices are such that many collectors of necessity purchase small pieces. Weight is more an issue now than ever before. Today many of the historical meteorites are for sell too. I find myself getting pieces of these even though they May be quite small. I got several at Tucson this year that I will probably look at tomorrow under the microscope and weigh. I won’t weigh them to check the dealer’s work but to keep good records myself. I got a couple of “firsts” at Tucson. A fragment of Weston with nice fusion crust. It is America’s first recorded fall, arriving on December 14, 1807. It provoked the famous remark from Thomas Jefferson. I also got a small piece of Coldwater, an H4 from Kansas. It was Harvey Nininger’s first stone, found in 1924. Both of these are small specimens in my collection . But, I will enjoy them very much. Part of that enjoyment will be in handling them during careful weighing.

 

Weighing , microscopy, photography, research, and cataloguing were all aspects of collecting years ago, I hope for most people they still are today. Times have sure changed. But, I would not go back. The amount of meteorite material available today is wonderful and rich. Collecting has never been more exciting. Enjoy your collections.

Till next time, Jim