LuDGATE — On a Proposed Analytical Machine. 89 



The Analytical Machine is under the control of two key-boards, and in 

 this respect differs from Babbage's Engine. The upper key-board has ten 

 keys (numbered to 9), and is a means by which numbers are communicated 

 to the machine. It can therefore undertake the work of the number-paper 

 previously mentioned. The lower key-board can be used to control tlie 

 working of tlie machine, iu which case it performs tlie work of a formula- 

 paper. The key-boards are intended for use when the nature of the 

 calculation does not warrant the preparation of a formula-paper or a 

 number-paper, or when their use is not convenient. An interesting illus- 

 tration of the use of the lower key-board is furnished by a case in 

 which a person is desirous of solving a number of triangles (say) of wliich 

 lie knows the dimensions of the sides, but has not the requisite formula- 

 paper for tlie purpose. His best plan is to put a plain sheet of paper 

 in the controlling apparatus, and on communicating to tlie machine the 

 known dimensions of one of the triangles by means of the upper key-board, 

 to guide the machine by means of the lower key-board to solve tlie 

 triangle in accordance with the usual rule. The manipulations of the 

 lower key-board will be recorded on the paper, which can then be used 

 as a formula-paper to cause the machine automatically to solve the 

 remaining triangles. He can communicate to the machine the dimensions 

 of these triangles individually by means of the upper key-board ; or he 

 may, if he prefers so doing, tabulate the dimensions in a number- 

 paper, from which the machine will read them of its own accord. The 

 machine is therefore able to "remember," as it were, a mathematical rule ; 

 and having once been shown how to perform a certain calculation, it can 

 perform any similar calculation automatically so long as the same paper 

 remains in the machine. 



It must be clearly understood that the machine is designed to be 

 quite automatic in its action, so that a person almost entirely ignorant of 

 mathematics could use it, in some respects, as successfully as the ablest 

 mathematician. Suppose such a person desired to calculate tlie cosine of an 

 angle, he obtains the correct result by inserting the formula-paper bearing 

 the correct label, depressing the proper number-keys in succession to 

 indicate the magnitude of the angle, and starting the machine, though 

 he may be quite unaware of the definition, nature, or properties of a 

 cosine. 



While the machine is in use its central shaft must be maintained at an 

 approximately uniform rate of rotation — a small motor might be used for 

 this purpose. It is calculated that a velocity of three revolutions per second 

 would be safe ; and such a velocity would ensure the multiplication of any 



