B66-575 GRAVITY INCLINOMETER IN ORIGINAL BOX. Deck Patent. The inclinometers patented by Thomas Deck of Toledo and manufactured by Deck's Gravity Level Co. have an unusually elaborate balancing mechanism to support the needle that tends to make it very sensitive but not very practical. This is the 30" version in its original box that has kept it in mint condition. The best Deck patent we've ever seen. Box has no label but original, missing ends and some tape. Fine 300-600