VOL. LXXVIII.] PHILOSOPHICAL TRANSACTIONS. 449 



account of the 1 moods, viz. the major and the minor, become 24, there are 

 hardly 14 that can be used; and for this reason most of the modern compositions 

 in musick are written in those keys. 



So far the common method of tuning answers some purpose ; for as long as 

 the performer is to play in certain keys only, it is much better to have them 

 tuned in the most advantageous manner, than to let those be tuned in a less 

 perfect way for the sake of others, which he does not intend to use. Hence the 

 great harpsichord players generally have their instruments tuned in a peculiar 

 manner, viz. so as to give the most advantageous effect to those concords which 

 they more frequently use in their compositions. And hence also the harpsichords 

 and organs are always tuned different from each other, unless they be tuned 

 by the same person with equal attention, and without any particular instructions. 

 This practice cannot conveniently be laid aside, viz. when the instrument is to be 

 tuned for solo playing; and for a certain style of music, it is very proper to tune 

 it so as to give the greatest effect to these combinations of sounds which are 

 mostly used in those compositions. But the case is far different when the in- 

 strument is to serve for accompanying other instruments in every sort of music, 

 or the voices of good singers; for then the disagreement becomes very audible; 

 and for this purpose the harpsichord or organ ought to be tuned according to the 

 above demonstrated temperament of equal harmony, which is the only one that 

 can possibly take place. 



When the compositions of old masters are performed in concert, and with 

 the organ or harpsichord tuned in the common manner, the effect is frequently 

 very disagreeable. This is particularly the case with the songs of Handel, Gal- 

 luppi, Leo, Pergolese, and others, who wrote in a great variety of keys, and 

 very often in those for which the common way of tuning is not at all calculated. 



XVL Description of a New Electrical Instrument capable of Collecting together 

 a Diffused or Little Condensed Quantity of Electricity, By Mr. T. Cavallo, 

 F.R.S. p. 255. 



One of the principal desiderata in practical electricity has been a method of 

 ascertaining the presence and quality of suchdiffused or weak electricity as could 

 not immediately aflfect an electrometer; of this nature is the electricity produced by 

 effervescences and other processes, also the electricity of the atmosphere in serene 

 and warm weather, &c. M. Volta's condenser, described in volume 72 of the 

 Philos. Trans, was the first attempt of the kind, and indeed when this instrument 

 is in good order it answers exceedingly well; but the difficulty of constructing 

 and of preserving it, added to the frequent uncertainty of the result, have oc- 

 casioned its being little, if at all, used by those who study the subject of elec- 

 tricity. Mr. Bennet's doubler, described in vol. 77 of the Philos. Trans, was 



VOL. XVI. 3 M 



