TOTAL_IDIOT

Mix corn startch and water. It's called 'oobleck'. Great example of exactly this.

Hello, I recently acquired this instrument, and I've not been able to figure out what it is. The label says: "Deflectometre JYC Jobin Yvon [crest] Type D2 No. 214 Paris-Arcueil" It is nothing like any other deflectometer I've found in research. See photos. Some knobs offer a very very fine adjustment of the lateral and vertical angles of unit. Others change lenses. The dark one is looking forward into hole where central eyepiece unscrewed from. There also happens to be a loose ball bearing inside instrument, about 8mm. Zero info on this to be found online! Hard to believe! Curious to hear feedback, thx in advance. Hope this is correct forum.