Hallo @sgdbdr,
This book, by the bavarian artillerie officer Schmoelzl, is based on a detailed description of russian experiments with this system. They wanted to introduce it. This russian article was translated into german and published in 1860 in a german military journal. This is the main source that Schmoelzl draws his info from. The eperiments in russia took place in 1858-1859. Apparently it was found that with the "normal" construction, the nose of the shell was moving a little above the ballistic curve, so that the center of air-resistance fell before the center of gravity of the shell. So the ogival part was made more heavy and the cylindrical wall was also strengthened and these 3 grooves mashined in the wall. All this to move the center of air-resistance a bit backwards.
Regards,
Bellifortis.
P.S.:
It's a great pity that both the digitized book and the 1860 journal are old Google scans, with most of the drawings missing. This is a worldwide problem with Google scans. I don't understand why german archives still use Google for digitizing their archives, as their system seems to be defective. Last year I contacted the "Deutsches Museum" in Muenchen for an old british patent. These patents had been removed for digitalisation by Google. When the scans arrived after many months, all the drawings were missing again. The helpful staff made fotos with his private telephone for me. This is a very huge problem. The digisats of millions of books have to be manually repaired. That will take dozens of years and cost billions, just for germany.
