work ▁mon or ail ▁to ys , ▁single - w he e led ▁and ▁gy ro - st abil ised , ▁were ▁produced ▁in ▁England ▁and ▁Germany . ▁ ▁Although ▁a ▁vi able ▁means ▁of ▁transport , ▁the ▁mon or ail ▁failed ▁to ▁attract ▁further ▁invest ment . ▁Of ▁the ▁two ▁vehicles ▁built , ▁one ▁was ▁sold ▁as ▁sc rap , ▁and ▁the ▁other ▁was ▁used ▁as ▁a ▁park ▁shelter ▁until ▁ 1 9 3 0 . ▁ ▁Sch er l ' s ▁car ▁ ▁Just ▁as ▁B ren nan ▁completed ▁testing ▁his ▁vehicle , ▁August ▁Sch er l , ▁a ▁German ▁publish er ▁and ▁phil anth rop ist , ▁announced ▁a ▁public ▁demonstr ation ▁of ▁the ▁gy ro ▁mon or ail ▁which ▁he ▁had ▁developed ▁in ▁Germany . ▁The ▁demonstr ation ▁was ▁to ▁take ▁place ▁on ▁Wed nes day ▁ 1 0 ▁November ▁ 1 9 0 9 ▁at ▁the ▁Berlin ▁Zo ological ▁Gard ens . ▁▁▁ ▁Sch er l ' s ▁machine , ▁also ▁a ▁full ▁size ▁vehicle , ▁was ▁somewhat ▁smaller ▁than ▁B ren nan ' s , ▁with ▁a ▁length ▁of ▁only ▁ 1 7   ft ▁( 5 . 2 m ). ▁It ▁could ▁accommod ate ▁four ▁passengers ▁on ▁a ▁pair ▁of ▁trans verse ▁ben ch ▁seats . ▁The ▁gy ros ▁were ▁located ▁under ▁the ▁seats , ▁and ▁had ▁vertical ▁axes , ▁while ▁B ren nan ▁used ▁a ▁pair ▁of ▁horizontal ▁axis ▁gy ros . ▁The ▁serv ome chan ism ▁was ▁hyd ra ul ic , ▁and ▁prop