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intervals from autumn to spring. They are always protected by tough coverings, hairy coats, or varnished with resin (examples, elm, willow, chestnut).

FLOWERS. The parts of the flower should be studied at first without dissection; later, the flowers may be taken to pieces carefully and the parts pinned out. The following will serve as useful types: buttercup, sweet pea, primrose, tulip, hyacinth, jonquil, crocus. Many bulbs planted in autumn can be easily grown in a schoolroom, under the care of the class: snowdrop, hyacinth, daffodil, narcissus, tulip. If a garden bed is avail. able it will be found a never-failing source of interest and pleasure; window boxes are a good substitute if the garden is not attainable.

In studying flowers and the uses of their parts much may be done by observation out of school. The bright colour and strong scent attract insects to visit flowers; the solid advantages they take away in the honey and pollen for food. The service rendered in return is the conveyance of pollen from one plant to another of the same kind. Noting these things leads to the understanding of pollination and the simpler methods by which it is effected. Some plants are pollinated by creeping and short-tongued insects (buttercup, arum, hemlock); some flowers (pea, vetch, clover) are specially adapted for bees, as the honey is concealed and bees have long tongues; the monkshood and foxglove are visited by humble-bees; pinks and honeysuckles by butterflies and moths. Trees, as hazels and poplars, have inconspicuously coloured flowers, but the flowers come before the leaves and in breezy spring so that the pollen is distributed by the wind. Grasses are another common instance of wind pollination.

coverings, and the seed being hard is undigested. Examples: yew and spindle, wood berries.

FRUITS. A collection of dry fruits should be made throughout the year. Many edible fruits can. be bought at any time. In spring the fruits of the primrose and marsh marigold are to be found; in summer those of the buttercup, violet, poppy, and dandelion; and in autumn a countless number of specimens are available, such as nuts of all kinds; clematis, rose-hips, haws, peas, beans, wallflowers, &c.

The other ways in which flowering plants multiply are chiefly by off-shoots from the stem. Examples are found in house-leeks, strawberries, couch grass. Artificial propagation by cutting shows also the reproductive power of the stem; begonias can be "struck" from a single leaf.

The above is a brief and general sketch of a plan of work which has been tried with success in a class of young children. Observations of what actually takes place in field and garden cannot fail to be a satisfactory foundation for future experimental work in laboratory botany. Young children have not the sufficiently mature minds to realise the significance of any but very simple experiments (such as have been described in this article), but they are keen and truthful students of outdoor sights and sounds, and faithful reproducers of what they see, especially if encouraged to illustrate their impressions by drawing and painting.

The chief points to be noted by young children are the division into classes of superior and inferior fruits-shown by reference to the orange and apple; the other great division into fruits which open, and fruits whose outer covering rots away or is broken artificially before the seed can come out. A large number of different fruits should be compared and the identity of parts noted under diversity of appearance.

The ways in which fruits open and seeds are dispersed give scope for careful observation. Good examples are seen in the poppy, iris, violet, honesty, pea, and many others.

The children should keep a "Nature Calendar," in which they can enter each day any new observation they make about the seeds and plants which they are growing or watching elsewhere. The children should also be encouraged to collect fruits, seeds, flowers, leaves, &c., and to arrange their finds in an orderly manner. As much work as possible should be done out of doors. The main object of such a course in Practical Botany is to train the power of accurate observation and precision of expression, but perhaps the greatest good is in awaking and stimulating an enduring love of Nature.

The dispersal of fruits and seeds by the wind is well shown in elm, maple, thistle, dandelion, and clematis; other fruits and seeds have rough, clinging surfaces, so that they are carried by animals. Examples: goose-grass or cleavers; "burrs" or burdock. Seeds carried by birds or other animals have generally attractive outside

ACETYLENE AS A LABORATORY HEATING AGENT.

ΤΗ

By A. E. MUNBY, M.A. Felsted School.

HE use of acetylene gas for lighting has extended so much during the last few years, and has proved such a boon to many who have no gas or electric light at disposal, that it is remarkable that more has not been done to produce suitable apparatus for using the gas for heating. In these days, when laboratories are springing up in so many small places where coal gas is either not obtainable or prohibitive in price, the possi bilities in connection with this use of the gas are very great, and have only quite recently been utilised. The gas, containing as it does 92 per cent. of carbon, requires, of course, special arrangements for its successful combustion. Calcium carbide, which produces the gas on contact with water, is now so well known that it is perhaps unnecessary to say anything about its production. The sole makers in this country, the Acetylene Illuminating Company, share with the British Aluminium Company the energy derived from the Falls of Foyers for producing their carbide, and the office of the former Company is at 3,

Victoria Street, S.W. A good deal of carbide is made on the continent and varies considerably in quality, the make of some firms being undoubtedly good. A good carbide should yield on an average four and a half to five cubic feet of gas per pound, and can be obtained delivered in most places at the present time for about £21 per ton, and as it is now usually packed in free non-returnable drums, this represents the total cost.

The choice of a generator for acetylene is rather beyond the scope of this article, but the report of the Committee on the Exhibition of Acetylene Generators held at the Imperial Institute in 1898, and printed by Mr. Trounce, 10, Gough Square, Fleet Street, or the elaborate work of Professor Lewes entitled "Acetylene," contains many drawins and valuable details of a score or more of generators now on the market. Where space, money and a good water-supply are all available, we think that a non-automatic generator, in which the whole of the gas to be used for a given period is generated at once, is to be recommended, especially as the pressure required for heating work, which, it must be noted, is equal to six inches of water as against about three inches generally arranged for a generator for lighting only, is readily obtained. If an automatic generator be employed, it is advisable to ascertain beforehand that this pressure can be obtained, and it should be borne in mind, and if necessary impressed upon the makers, that this additional pressure tends to the formation of more "after gas," so that the storage capacity of the gas holders should be increased. As regards the estimation of the size of generator required, it will be found that some makers have a tendency to over-estimate the output of their apparatus, and it will sometimes be found desirable, therefore, to install a machine a size larger than appears to be actually necessary on paper. Among automatic generators we may recommend that of Messrs. Thorn and Hoddle, 135, Victoria Street, S.W., as being compact and moderate in price, and we believe with their latest improvements quite satisfactory. We believe this firm to have been the first to modify a generator for heating purposes, and that they are alive to the requirements of the additional pressure. We have not found, however, that their generators run very well coupled together when the installation requires more than one of the largest size, one having a tendency to pump into the other. However, the firm claim to have improved the method of balancing, and where a second machine is kept merely in reserve, this of course does not form any objection.

The gas produced from any generator is not quite pure, and although it is used at present more often than not without any purification, it is becoming recognised that such a course is undesirable. The most important impurities in the gas are phosphoretted hydrogen, ammonia and benzene; the two former may be attributed directly to the carbide, and although they will be very small in amount in the case of a good carbide, such as that from Foyers, their removal is very

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desirable from a laboratory point of view, because they cause very rapid injury to platinum apparatus exposed to a Bunsen flame, and from an interesting paper in the Chemical Society's Journal for November, it would seem that the ammonia is probably not the lesser of the two offenders. last-mentioned impurity, benzene, may be produced owing to over-heating in the generator by the polymerisation of the acetylene; the objection to it from the heating point of view is that it tends to produce a zone of luminosity in the Bunsen flame.

Various purifiers have been proposed having for their general object the oxidation of the phosphoretted hygrogen, the neutralisation of the ammonia and the absorption of the benzene. Among others, bleaching powder and an aqueous acetic-acid solution mixed with chromic acid may be mentioned. The gas should pass through, not merely over, the purifier employed, which may be effected by making a solution, or milk, of the purifier with water, and exposing a large surface to the action of the gas by impregnating some indifferent substance such as coke or pumice with the liquid. We have made one or two experiments with the object of finding the value of these two purifiers in removing the luminous zone from a Bunsen flame and decreasing the deteriorating effect of the gas on platinum. So far as such experiments have gone, they seem to show that both considerably decrease the action of the gas on platinum, but that the acetic-acid mixture is the more efficacious. On the other hand, the bleaching powder has a marked effect in reducing the tendency to luminosity in the flame, though this effect does not seem to be very lasting; the acetic-acid mixture, however, appears to have no effect in this direction.

The construction of the Bunsen burner for acetylene involves a consideration of the diameter of the tube, which must be very small, to prevent "striking back"; the aperture of the jet, which has only to deliver about a quarter as much gas per time as in an ordinary Bunsen burner; and the gas pressure, which must be high, in order that the injecting power may be sufficient to cause the complete combustion of the gas. These factors, of course, are intimately connected one with the other, and admit of very little latitude. In the Munby burner, as produced by Messrs. Gallenkamp and Co., of 19, Sun Street, Finsbury Square, E.C., the diameter of the tube used is five millimetres, and the jet is capable of delivering about one cubic foot of acetylene per hour under the pressure employed, which is equal to a head of six inches of water. This burner, which is described in the Proceedings of the Chemical Society, 1896, No. 179, gives a full working flame for ordinary bench operations, which, as might be expected, is exceedingly hot, enabling heating operations to be carried on in very little more than half the time that is required when coal gas is used. For ordinary flame and spectroscopic reactions it is excellent, and the use of the blowpipe can be dispensed with for a great many small

operations. For example, a few grams cé zize, if heated for five minutes a covered crucible. will take fire and burn readily on the removal of the crucible 1.1. Naturally this neat has its deadvantages for some purposes, particiang necessitating acc.: ca. care 12 ng ass apparatus to the fame. jena gass stands we... of course, and a good Bohemian beaker or fask, with its contained by, may genera..y be exposed to the flame with impty, bi thicker German-glass vessels are very table to crack on sudden exposure to the fame. The fame cannot be turned down low without becoming Luminous when the Bunsens adjusted to give a sonluminous flame of good size, though small. condim nous Hames may be obtained by adjustment of the burner for this purpose alone, and this under so small a pressure as three inches of water. Ins Juminosity, on turning down the f-sized burner, enables a collar to be dispensed with, since for blowpipe work the luminous zone appears of self when the flame is lowered, but for all other reasons it is a disadvantage. Moreover, if the jet is enlarged or fed up to any extent, this m nosity may appear in the full fame. The jets d

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want occasional adjustment with a fine probe or a light hammer, but it is not found in practice that this occurs sufficiently often to form a serious disadvantage.

The various modifications of the Bunsen are not easy to imitate for acetylene, and the styles of the various burner-tops used for coal gas are quite useless. The acetylene Bunsen referred to is, however, furnished with a welt on which suitable tops may rest; these consist at present of an attachment to produce a fish-tail flame, and one to give a ring of small points for evaporations. A similar burner to the last, but one in which the points lie in a straight line also, exists. Very powerful combinations of several burners on the same stand may be made. A six-jet burner suitable for heating a small muffle-furnace is shown, together with the above forms, in the photograph which illustrates this article. One advantage which such multiple burners have over those for coal gas is that they can, owing to the small consumption of gas, be used off ordinary bench fittings with ordinary quarter-inch tubing.

Glass working, especially with potash glass, is considerably facilitated by the use of acetylene, but the flame tends to promote devitrification very

rapidly. The gas can be used with the blowpipe, and bere, of course, any apparatus used for coal gas is apputable, since the air supply can be reguated at w With a power air-supply the acetylene blowpipe becomes a most valuable weapon for producing very high temperatures, and if cxygen be used instead of air, the heat is probably only nvalled by the electric arc. Steel may be ready melted, and we can cite an instance in which a boue was meited through a small London-clay crucible of very reputable make, when oxygen was used.

Tacing the advantages and disadvantages of the gas for the laboratory beach together, there is no question as to the pre-eminence of the former. Certainly the laboratory walsh. we believe, has had the longest experience of this use of the gas wolld not now make an exchange in favour of coal gas. Perfection is yet to be attained, it is true, and we look to the manufacturers of carbide to supply the means for improvement by enabling us to dilute the gas a little from the start.

THE TEACHING OF HISTORY AND GEOGRAPHY IN FRUSSIA.

[graphic]

By A. HARGREAVES.

Realschule, Waldkirch, Baden.

N continuation of the article on "ModernLanguage Teaching in Prussia" in the September, 1901, issue of THE SCHOOL WORLD, the syllabus for history and geography may with advantage be described. The time devoted to history is about the same in all kinds of schools, and ranges from two to three hours a week over a seven-years' course. In the two years preceding this course, one hour is devoted to stories from German history and the Sagas from the oldest Greek and Latin history. From this point the syllabus is as follows:

History.

IV. 2-3 hours weekly.-Greek history to the death of Alexander the Great: Roman history to the death of Augustus. The period previous to Solon's death on the one hand and the war with Pyrrhus on the other is treated as shortly as possible (this in consequence of the preliminary work already mentioned). The most important points about the cultured Eastern nations are touched upon in connection with Greek history. A detailed description of the encounters between the Romans and Germans during the Republic is deferred till the next class. The most important dates are learnt.

Lower IIIrd. 2 hours weekly.-The golden age of the Roman Empire under the great emperors. German history from the first encounter of the Germans with the Romans till the end of the middle ages. The history of other countries is treated as far as is neceesary for a proper understanding of German history. Dates as in IV.

Repetition of ancient history based on the dates learnt.

Upper IIIrd. 2 hours weekly.-German history from the end of the middle ages till the beginning of the reign of Frederick the Great, with special reference to Brandenburg-Prussian history. Foreign history is touched upon where necessary for a proper understanding of the main subject. Dates as in IV. Repetition according to the dates learnt.

Lower IInd. 2 hours weekly.-German and Prussian history from the beginning of the reign of Frederick the Great to the present day. Foreign history as in Upper IIIrd.

Frederick the Great, the French Revolution, Napoleon I. (especially his relations to Germany), the fall and rise of Prussia, the wars of freedom (Befreiungskriege), the internal changes in Prussia, the re-arrangement of the political relations of Germany in 1815, the German Customs Union, the striving for political unity, the deeds of Kaiser William I., and the founding of the German empire are to form the chief part of the syllabus for this year. In connection with the German history and the lives of the various rulers, a comparison is to be drawn of the social, political and commercial development up to the end of the eighteenth century, giving prominence to the deeds of the Hohenzollerns, especially with regard to the elevating of the peasant, middle and working classes. Repetition of the Brandenburg-Prussian history according to the dates. learnt.

Upper IInd. 3 hours weekly.-Chief events of Greek history up to the death of Alexander the Great, and of Roman history up to the death of Augustus, touching lightly upon the East. Special regard is to be paid to the political, social, and civil relations which are to be grouped and compared. Repetition from German history according to dates to be learnt.

Lower Ist. The Roman emperors who had most influence on the world's culture. German history to the end of the Thirty Years War, with a deeper study of the political, social and civil relations. General idea of the rise of the states from 1648. Foreign relations which are of importance in the world's history, the Crusades, the movements for reform in the Church, the discoveries of the fifteenth and sixteenth centuries, are to be treated from more general points of view than in the IIIrd. Repetitions from ancient history according to dates learnt.

Upper Ist. The most important events of modern times, especially of Prussian-German history from the end of the Thirty Years War up to the present time. In connection with the lives of the great Elector Frederick William I., Frederick William the Great, Frederick William III., and Kaiser William I., comparative studies as in the lower IInd., but correspondingly deeper.

Thus we see that, contrary to the practice in English schools, the teaching begins with ancient history and then goes on to older German history, gradually working up to modern times, whence it

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returns covering the ground more fully. whole period of German history has been treated when the scholar has passed the lower IInd., after which many of the scholars leave.

METHOD. (1) The object of the preliminary instruction in the first two classes is to present the great heroes of the past to the heart and mind of the young scholar, in that way to develop his thoughts, and together with the stories from the Bible, to lay the foundation for historical perception and observation. The enthusiasm of the teacher and a sympathetic and vivid description of the heroes are the chief factors at this stage. A special course is not adopted, but it is. important that the prose and poetry of the German reading book should stand in close relationship with the biographies.

(2) For the other classes the great thing is to distinguish the instruction in IV. to Lower IInd. from that of the upper classes. For the former the acquisition of the chief facts, especially with reference to prominent persons and the chronological order of events, are of primary importance; while, for the upper classes, stress is laid on the development and comparison, from different points of view, of the matter already learnt. Even in the upper class the presentation of facts and their retention in the memory are not neglected, but together with outward events weight is laid on the internal relations, which naturally cannot be touched upon in the lower classes. Above all, the utmost importance is at this stage given to developing the capability of interpreting the present from the facts of the past, and of getting a clear idea of the relationship of the events to one another. Inducement is given to the scholars to esteem sufficiently such events in the mental and industrial life of the people which have had an influence on their development.

(3) Success depends chiefly on the personal qualities of the teacher, which only come into operation where the matter is freely treated and freely presented to the class.

Great tact and prudence are required in the selection and treatment of social and industrial questions (Lower IInd and Upper Ist). The justice of many of the present social demands is to be conceded, but the evil of all forcible attempts to change the social order is to be made clear.

The efforts of the ruling line on behalf of the people are presented wherever the history of the last hundred years offers an inducement to touch upon the social and political measures of other European States.

(4) The grouping of historical facts comparatively and from different points of view is recommended, especially for the repetitions, which are carried out in all classes to confirm the matter already learnt by heart without overburdening the scholars with unnecessary ballast in the way of dates. Books which present history in a connected form, an atlas, and a date book are used in classes IV. to Upper Ist. Free, connected descriptions by the scholars of what has already been learnt are practised wherever possible.

Geography.

The general aim is the acquisition of an intelligent understanding of surrounding nature and of maps, knowledge of the physical form of the earth, of the divisions of the inhabitants, and some knowledge of the principles of mathematical geography. The syllabus is as follows:

VI. 2 hours weekly.-Principles of general geography with reference to the immediate neighbourhood. Introduction to globes and maps. Elements of a knowledge of countries, beginning with the home and Europe. Books are not allowed.

V. 2 hours weekly.-Countries of middle Europe, especially the German Empire. A book is used. Further instruction with reference to the globe and maps as well as of reliefs. Simple sketches on

the blackboard.

IV. 2 hours weekly.-Europe except the German Empire. Simple sketches on the board and in copy books.

Lower IIIrd. 1-2 hours weekly.-Countries out of Europe. German colonies: comparisons with the colonies of other lands. Sketches as in IV.

Upper IIIrd. 1-2 hours weekly.-Repetition of German Empire. Sketches as in IV.

Lower IInd. 1-2 hours weekly.-Repetition of European countries except German Empire. Elements of mathematical geography. Sketch maps as in IV. In the "Realschulen" the most important commercial and traffic routes of the present time.

Upper IInd.-Upper Ist. 1 hour weekly. Repetition and principles of physical geography. Elements of mathematical geography correlated with the instruction in mathematics or physics.

METHOD. (1) The practical utility of the subject must be kept in view throughout. Physical geography is not given the preference over political, both are united as closely as possible in dealing with the different countries. Intelligent observation of the surrounding country as well as of reliefs and maps is brought into play, committing to memory whatever is considered necessary. Only a few round comparative numbers are to be learnt by heart.

(2) The first steps in physical and mathematical geography are confined to the neighbourhood of the school. When general principles have been understood they are represented by reliefs and the globe. The use of the map is then learnt gradually by the pupil. The wall map and atlas are later on the chief objects in class teaching. Books only serve as guides for preparation at home. Great attention is given to the correct pronunciation of proper names.

(3) In the lower and middle classes the same atlas is used. Large atlases are not allowed in the lower classes. Care is taken to see that the wall maps agree as much as possible with the atlases.

(4) Great importance is given to sketch drawing as an auxiliary to clear representation, but outline sketches and profiles on the board are alone expected. Map drawing at home is in general not

allowed. The scholars confine themselves to simple sketches during the time of instruction, the teacher himself first draws the sketches on the

(5) The teaching is in the hands of teachers who have made a special study of geography and is not divided among too many teachers. The repetitions in the upper classes of gymnasia, so far as physical and political geography are concerned, are in the hands of the teacher of history, the mathematical geography in the hands of the teacher of mathematics or physics.

The Emperor has several times insisted on the great importance of placing the teaching in the hands of properly qualified men. At most universities there are now professors of geography, and this branch may be taken as an optional subject by the students at their examinations.

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By W. W. F. PULLEN, M.I.M.E., Wh. Sc.
South-Western Polytechnic, Chelsea.
EXPERIMENT WITH THE FIVE-ROPE PULLEY
BLOCK.

BJECT OF EXPERIMENT:-To determine (1) The velocity ratio of the machine. (2) The general relations between the load and (a) driving force, (b) friction, (c) mechanical advantage and (d) mechanical efficiency.

Method:-It will be found very convenient to use the vertical post in Fig. 6, to aid in determining the velocity ratio by experiment. Of course, with the simple machine, it is an easy matter to calculate the velocity ratio, but as the experimental method is interesting and useful, it is given here in connection with the simple machine. The vertical post is made from a couple of strips of wood, separated by a distance piece at each end, forming a long slot in which the horizontal pointers P and N can be adjusted by thumb nuts. A small weight of (say) 14 lbs. is suspended from the load hook and another weight (say 7 lbs.) suspended from the spring-balance hook. These weights should be such that they will remain in any position in which they may be placed. Begin by moving the spring-balance end downwards so that the weight 7 lbs. is as near as possible to the floor but does not touch it. While in this position, set the upper

FIG. 6.

P

N

1 Concluded from p. 403, November, 1901.

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