ALS : Autograph Letter SignedMathematician, computer pioneer, inventor of the calculating machine. Autograph letter signed "C. Babbage", to Mrs. Ireland Blackburne of Westminster, asking whether his friend F [Francis] Offley Martin can join her party going to Richmond. 1 pg 4"x3-1/2". With the address leaf bearing Babbage's red wax seal showing a mathematical formula. Undated. Babbage write: "If you should not be overcrowded may I petition for him - I have not however give more than very slight expectation and if you are already full do not think of sending me the invitation. Ever truly yours, C. Babbage. P.S. I will endeavour to join you but am very doubtfull." In good condition.