278 DESCRIPTION OF ATKINs's HYDROMETER; 



Calculation in- The folution of this problem being almoft impoflible by any 



p P u p ^. lCt ° thlS application of mathematical formulas, itisofcourfe defirable 



to be enabled to obtain it infirumentally, or by infpeclion of 



Jfubl«. niCnCC tableS P revioufl y laid down from experiment; and the ufe of 

 the latter, under fuch circumftances as thofe in which opera- 

 tions of this kind are generally performed, having been found 

 JoluSon'prefer- ^ nconvement > i ts infirumental folution has been univerfally pre- 

 able. ferred. This has been attempted principally in two ways: by 



with hy a ^ rometer the hydrometer, with a multiplicity of weights adapted to the 

 weights, various corrections for temperature; and by the fame infiru- 



ment more fimply conftru&ed, fo as to indicate merely the 

 with a Hiding- fpecific gravity of the liquor; the necefTary corrections being 



applied by a fcale or Hiding-rule. 

 The latter moft The infirument here to be fpoken of is conftrucled on this 

 latter principle, which appears for many reafons to be the befi : 



5tWnrt°h dro- Th(? M rometer A B (P 1 - XV %• 3 ) is of brafs. It is eight 

 meter. inches in length, with an elliptical bulb an inch and a half in 



Square : ftem, diameter, and two inches long. The ftem is fquare, each fide 

 of the alphabet being about \ of an inch wide, and, when the infirument is in- 

 ©n one face, tended for fuch liquors only as are fpecifically lighter than 

 water, is engraved only on one face with the 26 letters of the 

 alphabet, and an Q, or zero, at the top and bottom ; oppofite to 

 each, and between every two of which, is a divifion for mark- 

 ing the point of the ftem which is cut by the furface of any 

 liquor in which it floats, the whole number of divifions being 

 55, as fhewn in the plate. The weight of the infirument is 

 and four about 400 grains, and it is provided with four weights, mark- 



ed 1, 2, 3, 4, weighing refpe&ively 20, 40, 61, and 84 grains, 

 to be applied as occafion requires on the thank of the infiru- 

 ment C, on which they are retained by the button or fixed 

 to Ae bulb w?tK wei S ht B - Thefe weights are fo adjutfed, that when with any 

 one weight, the one of them, as for infiance No. 2, the ftem of the infirument, 



next heavier -when floating in a given liquor, juft emerges to the lower divi- 



finks it to the _ • . ° ■ ° , ? ■ / | 7° r . . fc 



top of the ftem. " on O, it will, on changing the weight for the next heavier, 



No. 3, become immerfed exactly to the other divifion O, to- 



|!!m SuVhl^ wards its fuperior extremity. The fiem is by this means virtu- 



effect multiplied ally extended to five times its real length, and the number of 



With the divifions in effect augmented to 272. Thus without any weight 



weights finely at all, as reprefented in the figure, it would fink in a liquor 



applied, indicates wno f e fpecific gravity was .806, exactly to the upper divifion 



Specific gravities pj 



from .806 to V, 



S.COOJ 



