Stairway calculator

A device capable of calculating (a) the depth of treads in a stairway to be installed between lower and upper floor surfaces and having a given horizontal spread, and (b) the horizontal spread of a stairway comprising treads of given depth, comprising:

• first and second scale support surfaces adapted to slide with respect to each other;
• a first scale means on said first support surface, said first scale means comprising a plurality of indicia representative of numbers of treads;
• a second scale means on said second support surface, said first and second scale means being laterally adjacent to each other and said second scale means comprising a plurality of horizontal spread representative indicia;
• and
• indicia indicating means on said first support surface for indicating indicia on the second scale means;
• whereby, in operation, when said first and second scale support surfaces are slid with respect to each other to align indicia of the first and second scale means corresponding to the number of treads in the stairway and to said given horizontal spread of the stairway, respectively, said indicia indicating means indicates on the second scale means the depth of said treads;
• and
• whereby, in operation, when said first and second scale support surfaces are slid with respect to each other until said indicia indicating means indicates on said second scale means said given depth of the treads, indicia of the first and second scale means corresponding to the number of treads in the stairway and to the horizontal spread of the stairway, respectively, are aligned.

A device capable of calculating (a) the height of risers in a stairway to be installed between a lower floor surface, and an upper floor surface of given elevation above said lower floor surface, (b) the depth of treads in a stairway having a given horizontal spread, and (c) the horizontal spread of a stairway comprising treads of given depth, comprising:

• a body comprising first and second scale support surfaces spaced apart from each other;
• first and second slides mounted on said body between said first and second scale support surfaces and capable of sliding on said body, said first slide comprising a third scale support surface adjacent said first scale support surface, and said second slide comprising a fourth scale support surface interposed between said second and third scale support surfaces;
• a first scale means on said first support surface, said first scale means comprising a plurality of indicia representative of numbers of risers;
• a second scale means on said third support surface, said first and second scale means being laterally adjacent to each other and said second scale means comprising a plurality of elevation representative indicia;
• first indicia indicating means on said body for indicating indicia on the second scale means;
• a third scale means on said second support surface, said third scale means comprising a plurality of indicia representative of numbers of treads;
• a fourth scale means on said fourth support surface, said third and fourth scale means being laterally adjacent to each other and said fourth scale means comprising a plurality of horizontal spread representative indicia;
• and
• second indicia indicating means on said body for indicating indicia on the fourth scale means;
• whereby, in operation, when said first slide is slid on said body to align indicia of the first and second scale means corresponding to the number of risers in the stairway and to the elevation of the upper floor surface above the lower floor surface, respectively, said first indicia indicating means indicates on the second scale means the height of said risers;
• whereby, in operation, when said second slide is slid on said body to align indicia of the third and fourth scale means corresponding to the number of treads in the stairway and to said given horizontal spread of the stairway, respectively, said second indicia indicating means indicates on the fourth scale means the depth of said treads;
• and
• whereby, in operation, when said second slide is slid on said body until said second indicia indicating means indicates on said fourth scale means said given depth of the treads, indicia of said third and fourth scale means corresponding to the number of treads in the stairway and to the horizontal spread of the stairway, respectively, are aligned.