Plastic wrapping over a clock deadline number circle. https://www.rawpixel.com/image/13563779/plastic-wrapping-over-clock-deadline-number-circleView licensePneumatics: a heavy weight suspended from an evacuated sphere. Engraving. https://www.rawpixel.com/image/13954171/pneumatics-heavy-weight-suspended-from-evacuated-sphere-engravingFree Image from public domain license