-
Correspondence
AN OFFICE SEEKER OF SOME INITIATIVE Editor's Note: One of our correspondents, Dr. A. E. Marshall, 501 Fifth Avenue, New York City, interested in the history of The Much Woolton khool, founded some time in the 1500's and said to he "the oldest Lancashire elementary school," recently ran across a copy of a delightful letter preserved in the Warden's Books of Childwall. The letter.* which is printed below, is a marvelous example of the gentle art of letter writing as practiced in the 17th century and will doubtless he of interest to those educators who concern themselves with happenings of the past.
Childwall, Aug. 7, 1641 MR. CASE,It seemes you intend to teach a Parish Schoole here att Much Woolton, without the consent of the Parish; and indeed against the general1 vote of the Parishioners; i t is well knowne the house was built a t a common charge, and for likewise was the stocke then raysed and heene ever since continued and augmented: therefore we conceive that all have interest in the choise of a master. Now for your part: the truth is you have tyred us in this kind, above tenne yeares agoe: (as you have done other neighbour Schooles, hoth before and since): besides in thus goeing about to make new titles, you endeavour as much as in you lyes, to stirrup suits, factions and debates in the parish. Soe haveing seriously considered of this cause (which soe neereley conceives us), these are in a faire and loveing way to wish you in time to desist, and in case you be obstinate, then to give you notice that you are not to expect any schoole wages hut what you may obtaine by lawe. Thus haveing in the beginning given you this friendly warneing. Your loveing friends: (here follow the names of 59 Tithe Payers)
CENTIGRADE-FAHRENHEIT TEMPERATURE CONVERSION . DEAREDITOR: Recent notes in the JOURNAL OF CHEMICAL EDUCATION have discussed the advantages of different methods for calculating Centigrade-Fahrenheit temperature conversions. Joseph G. Blann, in the December issue,' uses thecquivalence of 21Z°F. and 100°C. as the point of reference in order to eliminate the troublesome 3Z°F. transition involved when one starts with the equivalence of 32°F. and O°C. In the February issue, hoth Alfred * B n o m , R. STEWART, "Notes on Childwall," Liverpool, 1919.
' BLANN,J. CmM. Eouc., 7, 2946-7
(Dec., 1930).
727
728
JOURNAL OF CHEMICAL EDUCATION
APRIL,1931
M. Ewing2 and Herman W. Woodsa call attention to the much simpler system of referring calculations to the equivalence of -40°F. and -40°C. In both places emphasis is placed on the graphical presentation of the temperature scales and the relative sizes of the two units. For the beginning student and his teacher, the graphical presentation of the relation between the two temperature scales is perhaps more important than the formula, whatever formula is suggested, because the student who has such a picture clearly in mind can make his calculations intelligently without the need of memorizing algebraic expressions or limiting himself to any one point of reference. The advanced student, or the practicing chemist or engineer, is not likely to come out with a wrong result in this simple conversion, but if he encounters it frequently he may welcome the following suggestion which further simplifies the arithmetic involved in converting temperatures from degrees Centigrade to degrees Fahrenheit. &en the Centigrade d u e , add to it one-tenth the difference obtained by subtracting that value from 160, and double the result. When a rapid conversion must be made mentally, this method will be found much easier to handle than any other, since it avoids the fraction 9/5 altogether and the value (160-°C.)/10 can always be obtained at once by inspection. For example: "C.
72.3
45
148
5W
17.460
The method is perfectly accurate and can be derived from the more familiar formula as follows: 9 OF. = -"C. 5 = 2'C.
= 2T.
+ 32 - 51-'C.
+ 32
+ 160 - 'C.
A similar method for the reverse conversion, viz., 'C. = % 'F.
(
- 320 9-
oF3
offers no advantage over the methods previously suggested because it still involves division bv 9. ROBERTN. WENZEL
EWINO,J. CHEM.EDUC., 8, 370 (Feb., 1931) a W o o ~ s itid., , 8, 370 (Feb.. 1931).
VOL. 8, NO.4
CORRESPONDENCE
729
DEAREDITOR: The criticisms made by Blannl concerning the 32' method of conversion seem to many teachers to be well founded. In teaching elementary physics for many years I have employed as the basis for a very simple rule the two facts, (1) that the relative magnitude of the two kinds of degrees is in the ratio 5/9, and (2) that the number minus 40' expresses the same temperature in both scales. Rule (1) To the given temperature add 40; (2) Multiply this sum by 5/9 or 9/5; (3) From this product subtract 40. The remainder is the desired temperature expressed in the other scale. For those who desire a mathematical formula the relation may he expressed
DEAREDITOR: In connection with the article by Blann' in a recent issue of the JOURNAL OF CHEMICAL EDUCATION, the results of the application of the following plan of temperature conversion to a teaching experiment may he of interest.
Drawing the diagram herewith reproduced as points are mentioned, the pupils fasten first the idea of three points of equivalence on the two scales. Then the degree-distance between these points is called to their attention, and the intervals indicated are reduced to lowest terms, fastening the concept of the 9:5 ratio. This ratio is tried out on a few examples, such as llO°C. being 18'F. more than 212'F.; this also shows the better students how they may use the 1.8 multiplier instead of 9/5 (or also 1.8 as a divisor
' BLANN,J.
CEEM.EDUC., 7, 2946-4 (Dec., 1930).
