246 



NATURE 



[July 14, 1892 



mouth of a bottle containing ammonia water. Hold 

 another tube over a bottle containing hydrochloric acid. 

 The tubes become filled with gases that rise from the 

 bottles, yet nothing can be seen in either tube. Place the 

 mouth of the first tube over the mouth of the second, and 

 invert. Do you see any evidence of the presence of 

 matter ? Was this matter in the tubes before they were 

 brought together.? If not, from what was it formed? 

 Which of the proposed questions does this experiment 

 answer .'' How does the experiment answer it ?" 



In many cases the questions asked are beyond the 

 powers of the average beginner to answer, but this is not 

 a serious objection if the book is used, as seems to be 

 intended, for class instruction in schools. For such use 

 it is admirably well adapted. Numerous questions and 

 examples are scattered throughout the text ; in the sections 

 of kinematics and dynamics geometrical treatment alone 

 is adopted, the student being supposed to be acquainted 

 with Euchd but not with trigonometry. 



The style is concise, but clear and accurate, and as the 

 book has not been written with the view of preparing the 

 student for any special examination it is refreshingly free 

 from any tendency towards cram. H. H. H. 



Receite, Conservation, et Travail des Bois. Par M. 

 Alheilig. (Paris: Gauthier-Villars et Fils, 1892.) 



This little book belongs to the useful series entitled 

 " Encyclopedie Scientifique des Aide-Mdmoire." The 

 author presents a remarkably clear summary of the 

 principal facts relating to wood, regarded from an 

 industrial point of view. Although iron and steel have to 

 so large an extent taken the place of wood in various 

 great constructions, wood is still, of course, needed in 

 vast quantities, and instruction in the proper way of 

 dealing with it. for industrial purposes must always form 

 an important department of technical education. M. 

 Alheilig has supplied a good text-book, the most valuable 

 characteristic of which is that its practical details rest on 

 a sound basis of scientific principle. He is especially 

 successful in the chapters on the tools and machinery 

 used in the working of wood. 



. Country Thoughts for Town Readers. By K. B. Baghot 

 de la Bere. (London : Simpkin, Marshall, and Co., 

 1892.) 



The greater part of this book consists of imaginary con- 

 versations between a Canon and "a city lawyer," who 

 spends two days with him in the country. The Canon 

 lectures his friend with an air of authority and 

 patronage which would not be particularly agreeable to 

 ordinary mortals. The city lawyer, however, is never 

 tired of thanking the great man for the knowledge he 

 communicates. The Canon's information is made up 

 chiefly of scraps of scientific commonplace, which, if 

 they can be of no particular service to any class of 

 readers, are at least harmless. 



■ A Synoptical Geography of the World. (London : Blackie 

 and Son.) 



. No effort has been made by the compiler of this hand- 

 book to present geography in an attractive form. The 

 volume consists of a number of bald statements which, 

 as here given, could neither excite interest nor form any 

 real addition to knowledge. It is not intended, however, 

 that the book shall be used apart from other means of in- 

 struction. It is meant to be taken " in conjunction with 

 a fuller text-book or the teacher's lectures." Used in this 

 way it may be of some service to students in the revision 

 of their work before examination. A good many maps 

 have been specially engraved to accompany the text. 



NO. I 185, VOL. 46] 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of NATURE. 

 No notice is taken of anonymous com?nunications.'\ 



An Acoustic Method whereby the Depth of \A^ater in 

 a River may be measured at a Distance. 



About two years ago, I wished to know from time to time 

 the rate at which a river was rising after a fall of rain. The 

 river was at a considerable distance from the spot where its 

 height was to be known. By means of the combination of 

 two organ pipes, and a tefephonic circuit, described in the fol- 

 lowing lines, I have been able to make the required m.easure- 

 ment within rather close limits. At the river station, an organ 

 pipe was fix^d vertically in an inverted position, so that the 

 water in the river acted as a stopper to the pipe, and the rise or 

 fall of the water determined the note it gave, when blown by a 

 small bellows driven by a very small water-wheel. A micro- 

 phone was attached to the upper end of the organ pipe ; this 

 was in circuit with a wire leading to a town station at some 

 distance ; at the town station there was an exactly similar organ- 

 pipe, which could be lowered into a vessel full of water while 

 it was sounding. By means of the telephone the note given by 

 the pipe at the river was clearly heard at the town station ; then 

 the organ pipe at this station was lowered or raised by hand 

 until it gave the same note. The lengths of the organ pipes 

 under water at the two stations were then equal, so that the 

 height of the water in the distant river was known. 



The determination can be made in less than a minute by any 

 one who can recognize the agreement of two similar notes. The 

 arrangement when first tested was so placed that the height of 

 water at two places near together might be easily compared. 

 I found that a lad with an average ear for musical sounds was 

 able to get the two heights to agree within one-eighth of an inch 

 of each other, while a person with an educated ear adjusted the 

 instrument immediately to almost exact agreement. The total 

 height to be measured was 17 inches. A difference of tem- 

 perature at the two stations would make a small difference 

 in the observed heights. For example, taking a note caused by 

 250 vibrations per second, a difference of 10° C. between the 

 temperatures of the two stations (one not likely to occur) would 

 make a difference of about 0'02 feet in the height, a quantity of 

 no moment in such a class of measurements. The organ pipes 

 were of square section, and made of metal to resist the action of 

 the water, 



Frederick J. Smith. 



Trinity College, Oxford, June 28. 



Waterspouts in East Yorkshire. 



On June 9, 1888, a waterspout was seen traversing the York- 

 shire wolds in the neighbourhood of Langtoft, which finally 

 spent its fury on the north-eastern side of a large basin-like 

 range of valleys, where a steep declivity barred its further pro- 

 gress. A single cutting or trench was made in a slight hollow 

 of the hill, and in this three large holes were scooped out of the 

 chalk, which was here composed of much rubble, about seven- 

 feet in diameter and depth. 



On July 3 of the present year, another waterspout has been 

 developed, and has again expended its energy on the same hill 

 as the previous one in 1888, a few yards only further south of 

 the former site, and, taking a trifle more easterly course, has cut 

 three parallel ditches or elongated pits in the solid chalk, two of 

 them twenty to thirty yards in length, and seven to ten feet deep 

 in the deepest portions, scattering the whole of the expelled 

 rock, amounting to many tons, to the foot of the hill. 



Serious floods were consequent, and the village of Langtoft, 

 which is situated lower down the valley, was terribly inundated 

 with a volume of water seven to ten feet in height, an immense 

 amount of damage being done, including the total demolition of 

 two cottages and a workshop. Fortunately no lives were lost 

 beyond several pigs, sheep, and a few hundred fowls. 



Driffield, July 9. J. Lovel. 



