Nov. 17, 1882.] 



♦ KNOWLEDGE • 



403 



of writing, of course, increases with practice, and as I am 

 a mere beginner, having only bought my instrument a few 

 weeks back, I am as j'et unable to say what rate can be 

 obtained with it. I have not yet learned to write with it 

 as fast as with the pen — perhaps I may never be able to do 

 so. For I am an unusually rapid writer. Mr. J. G. Petrie, 

 in a very interesting paper on " Reporting and Trans- 

 cribing Machines " (published by Jas. Wade, London, 

 price 6d.) says the maximum rate of writing is from thirty 

 to forty words per minute, but that few writers can keep 

 up that rate of writing for many minutes, and the writing 

 would then be far from legible. I find, however, I can, at 

 a pinch, write from forty to fifty words a minute, and keep 

 up a rate of from thirty to forty for quite a considerable 

 time, and as I get very clean proofs, I infer that com- 

 positors can read my writing. That does not prove my 

 writing legible in the ordinary sense, for compositors can 

 read almost anything. 



The following sentences quoted from the above-named 

 pamphlet were written at the rate of forty -seven words a 

 minute (sub-editor's timing). I will faithfully record, later, 

 how many mistakes the rather villanous writing has 

 caused the much-tried compositor to make. [I hope the 

 most skilful will be selected.] 



" Like everything else in this world, there is a right way 

 and a wrong way of manipulating the machine. The key- 

 i)Oard is composed of forty-four keys, arranged in four 

 rows, and these would be almost equally divided Vietween 

 the fingers of both hands ; the right hand manipulating 

 the right half of the keylioard, while the left hand works 

 the corresponding half. By using the three first fingers of 

 each hand, as I have said, a good style of playing the 

 machine can be acquired : and in order to gain facility for 

 its working, those words which are most in use in the 

 Janguage, amounting to a few hundreds, and which can lie 

 taken out of any shorthand instruction book, should be 

 practised over and over again until ease and facility in 

 vrriting them are acquired. The long bar, which makes 

 the spaces between the words, is always struck by the third 

 finger of the right hand, and in course of practice this 

 action becomes quite automatic."* 



To the last point in the above passage I venture to 

 demur. I find the bar much more conveniently struck with 

 the thumb of either hand. From the beginning, the Space, 

 which I had thought likely to be often omitted, was 

 readily and systematically marked, e.xcept when the rate 

 of work was pushed beyond that which practice had 

 rendered easy. 



It is claimed that with great practice fifty or sixty 

 words a minute can be printed with the "Writer," and 

 some thirty a minute, neatly and clearly printed, would be 

 better work than forty scrawled, and save much time, too, 

 in the long run. Then the work is so much plcasanter. 

 One can sit squarely up to the instrument, and take a good 

 full breath at each inspiration, instead of filling the merest 

 comer of the lungs, as when busily engaged in writing — 

 especially when trying to write very quickly. 



Russia axd tue Telephone. — We do not hear much of 

 any progress being made with the telephone in the Russian 

 Empire. A facetious contemporary explains this circum- 

 stance by the fact — if it is a fact— that the exclamatory 

 halloo ! with which, as everybody knows, all telephonic 

 conversation must begin, is, in the Russian language, 

 rendered Tzijakanfitkrajanjanzski ! which, of course, no 

 telephone yet invented can pronounce. 



» Total number of errors in author's first proof — 0. — K. A. P. 



•08 



:= -M 



THE AMATEUR ELECTRICIAN. 



ELECTRICAL MEASUKEMEXT.—V. 



THE question which next presents itself is, having a 

 certain number of cells, and a certain line-resistance to 

 be overcome, what will be the most advantageous mode of 

 joining the cells together so as to get the greatest possible 

 amount of work out of them 1 By taking an example we 

 shall see that the best result is obtained when the two 

 resistances, internal and external, are nearest to equality. 

 Suppose we have 40 ordinary Daniell cells, each having 

 an E M F (electro-motive force) of one Volt, and each ofier- 

 ing a resistance of 10 Ohms to work a circuit of 100 Ohms 

 resistance. When joined up in series we get 

 E 40 



R + R'~400-flO0' 

 If we divide the battery into two series of 20 cells each, 

 and then put them side by side for quantity (see Fig. 1, 

 KxowLEDCE, No. 51) we get 



_E__ 20_ 



R-l-R'~100-|-100" 

 The E M F becomes 20 Volts, because there are only 20 

 cells in series. With a single set of 20 cells the value of 

 R (internal resistance) would be 200 Ohms, but as we 

 practically double the size of the cells by joining a similar 

 set of 20 cells with it for " quantity," that value is reduced 

 to 100 Ohms ; so that whereas 40 cells in series give 400 

 Ohms, the same number joined up as just described give 

 only 100 Ohms. 



If now we divide the full battery into four sets of 10 

 cells each and join all these sets side by side, we get 

 E 10 ^ 



R-fR'~ 2.5 -f 100 ~ ■"* 

 In this instance R becomes 25, instead of 100, because 

 instead of one battery there are four batteries side by side, 

 quadrupling the conductivity or quartering the resistance. 

 It is here clearly demonstrated that, while in the first 

 case the battery resistance exceeded the line res-istance, 

 and in the third case ii<v' rersd ; in the second instance the 

 two resistances were exactly equal, and as was predicated, 

 the greatest strength of current was then obtained. This is 

 well worthy of thoughtful study, not so much, perhaps, for 

 working out problems, as for firmly imprinting upon the 

 mind the very important deduction laid down. 



In deciiling on the form of battery to be used for any 

 particular kind of work, resort should always be made to 

 the simple formula we have been explaining. It frequently 

 liappens, however, that we cannot obtain a current of given 

 value in Volts and Amperes without having a greater or 

 less ditlcrence between the internal and external resist- 

 ances. Let us suppose, for instance, that we want to 

 illuminate a small room with an incandescent lamp which 

 ofi'ers a resistance of 30 Ohms, and absorbs a current of 

 1 -2 Amperes, with an E M F of 40 Volts. Suppose we 

 tried it with 40 Daniell cells, we should get 



4Wr30=-<^»3' 

 wliich is a long way short of what we require. In fact, in 

 order to procure the required current it would be necessary 

 to place 100 sets of 40 cells each, side by side, in order to 

 reduce R to the value most useful for our purpose. Let 

 us next try a Bunsen battery, each cell having an E M F 

 of 2 Volts ; 20 cells joined together in succession or series 

 will give us 40 Volts. The internal resistance is very low, 

 20 cells giving :? Ohms, or 15 per cell. We therefore get 

 E _ 40 _ J.., 

 R + R'~3-f30~ 

 There is here a considerable difference between the internal 



