Yards of tenement houses hereafter erected on corner lots must be not less than ten feet deep, and extend across the full width of the lot. On interior lots the depth of the yard is to be proportioned to the height of the building. For houses sixty feet high the yard must not be less than twelve feet deep, and for every twelve feet or fraction thereof beyond sixty feet in height the yard must be increased one foot in depth. Similarly for every twelve feet in height less than sixty feet, the yard may be decreased one foot, but it shall in no case be less than ten feet deep. On corner lots, where it is intended to have stores on the ground floor, the yard may start from the second tier of beams. Where a tenement house runs through from one street to another street, and the lot on which the house is situated is less than seventy feet in depth, no yard space is required. Where the lot is over seventy feet deep, and not over one hundred feet, the yard need only be twelve feet deep for a building sixty feet high, and shall be left through the center of the lot. Where lots that are over one hundred feet in depth run through from street to street, the yard must be left through the center of the lot, and must be twenty-four feet deep, and must increase with the increased height of the building.