332 PHILOSOPHICAL TRANSACTIONS. [aNNO 1747. 



sorts of grain, which were never before known in that part of the world, and 

 which not before some length of time were found out, and coveted by some of 

 these migratory birds. No wonder that this grain should not be immediately 

 known to birds of distant regions ; for above half a century passed from the time 

 of cultivating wheat, rice, and barley, in Virginia and Carolina, before those 

 grains were found out and frequented by these foreign birds, of which one has 

 only lately made its first appearance in Virginia, as Dr. Mitchel informed him • 

 viz. that being in his garden a bird flew over his head which appeared with un- 

 common lustre, and surprised him the more, not having seen the like bird be- 

 fore. Mentioning this to some of his neighbours, he was told by them, what 

 afterwards was confirmed to him by his own observation, viz. that these exotic 

 birds had only within these few years appeared in Virginia, and had never been 

 observed there before. 



They arrive annually at the time that wheat, the fields of which they most 

 frequent, is at a certain degree of maturity; and have constantly every year, 

 from their first appearance, arrived about the same time in numerous flights. 

 So that they have acquired the name of wheat-birds. 



Of a Machine to write down Extempore Voluntaries, or other Pieces of Music. 

 By the Rev. Mr. Creed. N° 483, p. 445. 



The following is a demonstration of the possibility of making a machine that 

 shall write extempore voluntaries, or other pieces of music, as fast as any master 

 shall be able to play them on an organ, harpsichord, &c. and that in a charac- 

 ter more natural and intelligible, and more expressive of all the varieties those 

 instruments are capable of exhibiting, than the character now in use. 



Maxim 1 . — All the varieties those instruments afford fall under these 3 heads : 

 1st, the various durations of sounds, commonly called minims, crotchets, &c. 

 2dly, the various durations of silence, commonly called rests. 3dly, the various 

 degrees of acuteness or gravity in musical sounds, as a re, b mi, &c. 



Maxim 1. — Straight lines, whose lengths are geometrically proportioned to 

 the various durations of musical sounds, will naturally and intelligibly represent 

 those durations. Ex. gr. ' 



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