It is a hot August whether these days here around, the temperatures above 30 degrees C for almost two weeks.Only nights are a bit cooler,we stay awake quiet late. Yesterday evening was the same,we were watching TV as a strange visitor came in-a yellow, huge moth was flying across the room almost like a bird,then he sat down on a plant and remained there long enough for us to make some pics.We’ve seen such a big moth here for the first time-and have been very impressed by his story.
Yamamai or Japanese Oak Silkmoth has been cultivated in Japan for more than 1000 years,its silk is white,elastic,durable and very expensive.Adult moth has a wingspan of 10-15cm.Its larvae feed on quercus while the adult moth doesn’t eat at all,he has enough energy to fly for a couple of days and to reproduce,then he dies.In the middle of 19-th century family Mach has settled in Veliki Slatnik (Slovenia).In 1866 Johann Mach imported yamamai eggs to start with the production of Shantung silk .The business didn’t succeed ,but the yamamai butterflies succeeded to survive in new habitat ,even more, from Veliki Slatnik they spread to whole Balkan, Italy,Austria,they have been spotted in Germany. Johann Mach and his wife are buried for a long time.Their grave at the cemetery of Veliki Slatnik is almost forgotten. Yet whenever yellow yamamai appears here around, he brings with him a story of family coming from far to live in these rural area,with a strange idea of producing silk and leaving this beautiful moth to fly further to Europe.And there is still another story yamamai brings with him, a story of Mach son ,loving the land around fathers farm that much that he was returning back home for his holidays.Professor of physic at the universities of Graz,Prague,Vienna wrote some of hist best works at the farm where his father explored the conditions to suit yamamai silk production best.And who this son was? Ernst Mach, great physic and philosopher of time,Mach number is just one of his many contributions.So from now on when I will see a yamamai I will remember Veliki Slatnik, silk and Mach number……..
Ernst Mach (German pronunciation: [ˈɛɐnst ˈmax]) (February 18, 1838 – February 19, 1916) was an Austrian physicist and philosopher, noted for his contributions to physics such as the Mach number and the study of shock waves. As a philosopher of science, he was a major influence on logical positivism and through his criticism of Newton, a forerunner of Einstein‘s relativity.from:
In fluid mechanics, Mach number ( or ) (generally /ˈmɑːk/, sometimes /ˈmɑːx/ or /ˈmæk/) is a dimensionless quantity representing the speed of an object moving through air or other fluid divided by the local speed of sound. It is commonly used to represent the speed of an object when it is traveling close to or above the speed of sound.from:
|Antheraea yamamai superba|
Guérin-Méneville, 1861[verification needed]