computer 60 pressure manifold 62 supplies pressurized fluid to each cylinder 22 through a respective valve 62 a not all of valves 62 a are shown in fig3 control computer 60 also controls a return valve on each cylinder 22 through line 60 b not all of lines 60 b are shown in fig3 when the return valve is opened by control computer 60 fluid runs through a respective return line 66 a to fluid reservoir 66 only one of the 24 return lines 66 a is shown in fig3 fluid from fluid reservoir 66 is pressurized by electrical or diesel pump 64 before it is supplied to the pressure manifold 62 control computer 60 has several programs to control multiple sets of the cylinders 22 as discussed above in the embodiment shown in fig4 8 half of cylinders 22 are controlled to extend and retract together and the halves are alternated for each level between 1 right and left half and 2 front and back half thus control computer 60 at has programs to extend and retract 1 the right half of cylinders 22 2 the left half of cylinders 22 3 the front half of cylinders 22 and 4 the back half of cylinders 22 additional commands such as all extend and all retract can also be programmed into control computer 60 further if each level includes more than 2 blocks additional commands will be needed to control smaller subsets of cylinders 22 accordingly a tower 80 may be constructed.