162 REPORT OF NATIONAL MUSEUM, 1890. 



was sent by Professor Morse, May 24, 1844, has been presented by Mrs. 

 Amanda Vail, widow of Alfred Vail, the associate of Professor Morse, 

 who received and deciphered that historic message at the Baltimore 

 end of the line. The original telegraphic instrument by which the 

 message was sent, has been in the collection for some time. 



One of the first dividing engines, designed and constracted by Jesse 

 Eamsden, of Piccadilly, London, England, in 1774-'75, together with 

 the apparatus, with which the screws and gear-cutters of the machine 

 were made, was deposited by Dr. Henry Morton, president of Stevens 

 Institute of Technology, Hoboken, New Jersey. 



A sextant, which was graduated by this dividing engine in 1775, was 

 so accurate that the English Board of Longitude, " ever ready to 

 remunerate any successful endeavor and to promote the lunar method 

 of determining longitude by sea," conferred a reward of £615 to Eams- 

 den on condition that the engine should be at the service of the English 

 instrument makers, and that he should publish an explanation of his 

 method of making and using it. A quarto pamphlet containing this in- 

 formation was published in 1777, with a preface prepared by Nevil 

 Maskeline, astronomer royal, dated Greenwich, November 28, 1776. 

 It is interesting to note in this connection that the circles of the great 

 theodolite, with a 36-inch telescope (still preserved at Greenwich), 

 which was specially constructed in 1785 for the Trigonometrical Sur- 

 vey of Great Britain, was graduated by this engine. 



The machine by which the endless screw for the dividing engine was 

 cut, is of the greatest importance, for it is one of the earliest applica- 

 tions of the principle of changing the lateral speed of the tool by differ- 

 ential wheels in screw-cutting — the method now used in the slide-rest 

 of the machinist's lathe. This machine, which has been developed and 

 improved, has proved of incalculable advantage to the mechanical engi- 

 neer and machinist. 



CONDITION OF THE COLLECTION. 



The study series, composed mainly of graphic illustrations, has been 

 increased by a number of photographs, prints, etc. 



The card-catalogue of the collection, commenced during the year, has 

 been finished far enough to indicate that the approximate number of 

 specimens in the collection is 1,250, occupying 880 entries in the cata- 

 logue. 



It is hoped that this catalogue will be completed during the next 

 fiscal year. 



