Show thermometers there are four principal thermo thermometers thermometer mete rs which differ from each other only in the manner in which they are graduated radiated they are called by the names of their their inventors fahrenheit ren heit romer sometimes spelled ltd lid reaumer atimer celsius and de lisle in all alt countries where the english la language guage is spoken that of fahrenheit is adopted the french have within a few y years yearb e arb made use of 0 that of celsius which they c call cail all ali the centigrade thermometer ther e centigrade in germany that of romer is is gener generally ally aily used and in Russia that of de lisle we will give a brief description of the graduation of each in the thermometer of fahrenheit the difference of the altitudes of the mercury at the f freezing ree zing and boiling points of water is divided into equal parts which are called de degrees rees a and nd this division is carried above and below balow these points as far as may be necessary at 32 below the freezing point of water fahren heit marked the commencement or zero of bs hs r cale scale believing that at that point ther there ewas was a total absence of all heat water therefore according to his thermometer freezes at 32 and boils boila at 2121 in the thermometers of romer and celsius the zero point is placed at the freelin freezing g point of water and in each the scale is continued and numbered both ways from this point the numbers below zero being called caled negative and marked with the negative algebraic sign so far they agree but they differ in the mode of their graduation as follows in the difference of the heights of the Iner mercury cury between the freezing and boiling boiling points of water is divided into 80 while in that ilat of celsius it is divided into 1001 loo and hence its title of centigrade in the thermometer of de pe lisle bisle the zero point is placed at the boiling bolling paint pint of water the distance from which to the freezing point is divided into 1501 and the scale is numbered both ways from the boiling point the follo following winz table will show the degrees of each ach scale at the ahe remarkable points of the freezing and boiling of water fah rab 0 ont nt rom BOTH do D lule luie freezing 32 0 00 0 ilo llo boiling fling 2120 gig 80 0 As the thermometer of de lisle is used only in russia and as russian scientific works are seldom quoted we will not therefore dwell upon it it may however be useful to give rules for reducing the degrees as given by each of the remaining thermometers into the equivalent degrees of the other two to enable us to understand quotations from french and german scientific works to reduce the degrees of the centigrade thermometer io to those of fahrenheit rule multiply the cent centigrade rade degrees b by r 9 and divide the product ey by 5 if the centigrade rade derees degrees were minus the quotient must fe be deducted deduc deducted fed led from 32 but if the centigrade degrees were plus the quotient must be added to the remainder or sum as the case may be will be the equivalent degrees of fahrenheit it will sometimes happen that centigrade 6 degrees when minus and operated upon as above will give a quotient grea greater ter than 32 and which therefore can not be deducted from it in this case deduct 32 from the quotient and the remainder will be the degrees of fahrenheit negative or below zero example 1 10 10 centigrade 14 fahrenheit f for or 10 X 9 gos gov and 90 00 5 equal which deducted from 32 leaves fahrenheit heit belt as above example 2 50 centigrade fahrenheit for 50 X 9 0 and 5 90 which added to 32 gives 1220 fahrenheit example 3 32 centigrade 25 35 3 5 fahrenheit for 32 K X 9 2880 and 15 5 X 57 35 3 5 which being greater than 32 we deduct 32 from it which leaves 2535 2335 25 3 5 51 fahrenheit negative or below zero to reduce fahrenheit to centigrade rule if the degrees areilus are plus pius or above zero take the difference between them and if they are negative or below zero add 32 to them multiply the ehg difference or sum as the case casp may be ly by 5 and divide the product by 9 and the quotient will bethe equivalent degrees emhe cent grade if the given number of degrees be more than 32 the centigrade dege degrees a will be plus if less than 32 or if nega negative alive the centigrade degrees will be minus ex example TP 6 1 1 14 4 fahrenheit a sio centigrade ra d e f 1324 of A 14 1411 a 18 and 18 xa X 5 fa 90 and 90 gog 61 6 1 9 los 10 which because 1411 14 1 I 1 is s liss less less than 32 J be becomes oj es e exam example lc al 21 2 fahrenheit 50 centigrade for or 1220 32 a 90 goa and 90 X 5 which divided by 9 gives ives 50 centigrade I 1 which is plus because is greater than 32 example 3 25 35 35 fahrenheit 2 20 centigrade for 25 35 3 5 X 57 35 3 5 which multiplied by 5 and this divided by 9 ives 32 centigrade because the fahrenheit degrees agrees are below zero to reduce re d uce ro romer mer into fahrenheit the ile multiplier in this case is 9 and the divisor 4 in other reject respects s the rule la Is precisely the same ag as that for I 1 or reducing a centigrade to fahrenheit example L 1 romer homer 77 fahrenheit for 20 X 9 1809 4 45 which be cause the degrees of romer are arenius plus pius must be added to 32 which gives fahrenheit as above example 2 3 romer IQ fahrenheit for 46 which because the degrees rees of romer are re negative must be deducted f from rom 32 leaving 25 1 fahrenheit example 3 25 romer fahrenheit for and 2 from which deducting 32 we have 24 1 fahrenheit to reduce fahrenheit to romer the multiplier in this case is 4 and the divisor 8 9 in other respects the rule agree with that before given for reducing fahrenheit to centigrade examples 25 loland which divided by 93 Romer as above example 2 77 fahrenheit 20 romer for 77 and which divided by 9 gives romer example 3 2410 fahrenheit 25 romer for 2410 1 32 and which divided by 9 gives 2511 25 romer to reduce romer to centigrade multiply the degrees of romer by 5 and divide the product by 4 the quotient will be the i equivalent degrees of centigrade example 20 romer a 25 centigrade for and nd loo 1004 4 25 2 centigrade 21 to reduce centigrade to loromer romet romer multiply the degrees of centigrade by tand band divide the product by 5 6 the quotient wi will I 1 be the equivalent de degrees grees of romer example 25 cen centigrade tirade 20 romer for and 1000 romer |