Report on the Examinations in Physiography.

Section I. of Stage 1.

EVENING EXAMINATION.

Results: Passed 126; Failed, 111; Total, 237.

A.

Q. 1. What is meant by the statement that matter is indestructible? Illustrate your answer by considering the burning of a candle, and explain carefully how you would perform an experiment with a candle to verify the law.

Many of the answers to the first part of this question were incomplete. The experiment of burning a candle so as to collect the products of combustion was well described, but the way in which this experiment illustrated the indestructibility of matter was not well answered.

Q. 2. Describe and explain the action of a common balance.

If the length of the right arm of a balance is 20 centimetres and that of the left is 2011 centimetres, what weight will have to be placed in the right-hand pan to counterpoise a weight of 100 grams placed in the left pan?

The essential points of a common laboratory balance were generally omitted. Most candidates gave an elementary description of an ordinary pair of scales. The underlying principle of the lever was known and the second part of the question was well answered.

Q. 3. The wheel of a bicycle is 30 inches in diameter and is observed to make 100 revolutions in a minute. What is the speed with which the bicycle is moving? What are the speeds of the points on the tyre of the wheel which are at a given instant at the highest and lowest points respectively.

The first part of this question was well answered. The second part was only occasionally attempted and only once was the correct answer given. Q. 4. What is the function of the pendulum of a clock?

What would be the effect on the rate of the clock (1) of increasing the size of the bob, the length of the pendulum remaining constant, (2) of increasing the length and keeping the size of the bob constant?

The first part was badly answered. The function of the pendulum is to "tick seconds" and the function of the pendulum is "to regulate the clock" were the common answers. The second part was well done.

B.

Q. 5. What is meart by the term specific heat?

Describe carefully an experiment to show that iron and lead have different specific heats.

A few correct definitions of specific heat were given, but the majority missed out one or more essential points in the definition. The unsatisfactory method of showing the difference in the specific heats of iron and lead by dropping balls of these substances at a high temperature on to a sheet of beeswax was often given.

Q. 6. Water is said to boil at 100° C. ; criticise this statement and point out where it is defective.

Describe an experiment to illustrate your answer.

Well done. The effect of change of pressure was generally known and good illustrations were given.

Q. 7. What are the laws of refraction of light?

Explain, illustrating your answer by a carefully drawn diagram, why the water in a swimming bath appears shallower than is actually the case.

Snell's law was only given two or three times. The majority of the candidates stated that when a ray of light passed into a denser medium it was refracted towards the normal and vice versa. The second part of the question was not well answered, many of the candidates, in order to explain the phenomenon, finding it necessary to assume that light in passing into a rarer medium was bent towards the normal. The apparent position of a point upon the bottom of the bath was seldom given, the majority of the candidates simply indicating the direction in which it lay.

Q. 8. Describe how a spectrum may be projected on a screen, and explain carefully the functions of each of the parts of the apparatus you would employ.

What will be the appearance of the spectrum if the slit is opened very wide?

The lens was generally omitted. When it was introduced its function was not explained. Nearly all the diagrams given were very badly drawn and out of proportion. The appearance of the spectrum with a wide slit was given as "blurred" or "indistinct," but the reasons were not forthcoming.

C.

Q. 9. Describe, giving a sketch of the apparatus employed, how you would remove oxygen and water vapour from atmospheric air. Several candidates explained how to remove oxygen from the air, but only a few knew how to get rid of water vapour.

Q. 10. What is the composition of iron rust.

Describe an experiment to prove the composition of iron rust. Fairly well answered.

Q. 11. Describe how you would prepare carbon dioxide, giving a sketch of the apparatus.

Describe three experiments illustrating the properties of carbon dioxide.

Very well done.

Q. 12. Describe the composition and general properties of limestone, lime, common salt, washing soda, and caustic soda.

The composition and properties of limestone, lime, and common salt were satisfactorily given. Washing soda and caustic soda gave trouble to

many.

DAY EXAMINATION.

Results: Passed, 108; Failed, 76; Total, 184.

A.

Q. 1. What are the principal features of difference between the metric and the British systems of weights and measures? If 1 pint = 567 litre, and 1 gram = '002204 lb., find the weight of a pint of

water.

Fairly well done. The commonest mistakes were (1) the metre represents a certain natural length exactly and could be easily replaced if lost; (2) no relation whatever between British units of weight and volume.

Q. 2. A piece of sulphur at one end of a balance beam is in equilibrium with a piece of brass at the other end. How will the horizontality of the beam be affected when (1) the brass alone, (2) the whole system-beam, brass and sulphur-is immersed in water?

Usually done correctly.

Q. 3. A railway train is moving round a circle with uniform velocity. What are the forces which act upon it? Why must the outer rail be raised above the inner?

Not more than five candidates realised that the centripetal force is exerted upon the train by the rails. This force was described as “pulling the train from the centre of the curve." The statement that inertia was one of the forces was frequent. No one knew exactly the effect of elevation of the outer rail. Most stated only that it was there to prevent the train running off the line.

Q. 4. What is meant by the energy of a swinging pendulum? Is the energy the same when the bob is at the top as when it is at the bottom of its swing? If not, how do they differ?

Many knew that the energy was sometimes kinetic and sometimes potential; but the names were confused, and very few knew that the sum of the two is nearly constant throughout the swing.

B.

Q. 5. Explain how the fixed points are marked on the stem of a thermometer. What is the effect on the indication of a thermometer immersed in boiling water of adding some common salt to the water?

A good many omitted to say that the ice should be melting. One or two candidates referred to the facts that the ice should be pure, and that the barometer should be read in the case of the boiling point.

Q. 6. It is possible to extinguish the flame of a candle by passing over it (without touching the wick) a short coil of thick copper wire. Explain why the candle is extinguished?

Most of the candidates knew the general lines of the explanation; but many answers were incomplete in the respect that the necessity for the temperature to be above a certain value for combustion to continue was not stated.

Q. 7. If you look at a telegraph post through a slab of glass held some distance from the eye you notice that the part of the post seen through the glass varies in position as the glass is rotated. Draw a picture to illustrate this effect, and explain it.

Very seldom attempted.

Q. 8. A dark blind covers the window of a room so that light only enters by a narrow horizontal chink at the bottom. How would you hold a glass prism so as to see the chink through the prism, and what would the appearance be like? Draw a picture to illustrate your answer.

There were a few incomplete answers.

C.

Q. 9. Describe any methods you are acquainted with for preparing hydrogen. What are its physical and chemical properties?

Better done than any of the other questions. The commonest mistake was confusion of the physical and chemical properties.

Q. 10. What is common salt"? What are its properties? What experiments would you make to ascertain its nature?

Only a few knew how to show that salt contains sodium and chlorine.

Q. 11. What would be the effect of putting into an oven and raising to a high temperature, (1) wood, (2) iron, (3) marble, (4) washing soda? Would the results be the same if the substances were heated in a Bunsen flame?

Many gave only physical effects, e.g. change of temperature, colour and state in the case of iron, and most of the answers were incomplete.

Q. 12. How does spring water generally differ from rain water? Why is pure rain water not pleasant to drink? How can it be made more palatable?

It was sometimes stated that the soil acted as a filter in the case of spring water. Softness and hardness were frequently mentioned without being understood, e.g., rain water was stated to have a soft taste.

Results: 1st Class, 759; 2nd Class, 671; Failed, 616; Total, 2,046.

There is a consensus among those who have read the papers that, on the whole, they represent a marked improvement on those of former years. There is much less of the hopeless rubbish which was at one time so characteristic of the answers in this stage. But while on the whole satisfactory, the papers seem to indicate a certain amount of neglect of some fundamental subjects to which the attention of the teachers ought to be directed. Of these, the most important is represented by Q. 4, which asks for an explanation why it is wrong to represent the composition of atmospheric air by a formula, such as NO. For years past the Examiners have been endeavouring to suppress this practice, which was at one time very common, and was evidently the result of widespread erroneous teaching. Even now the answers to this question show, in a large proportion of cases, that the students do not apprehend correctly the nature of the error involved in the use of a formula. It seems to be thought that the formula is to be objected to on the ground that it ignores the small amounts of water vapour, carbon dioxide, and other gases present, along with the oxygen and nitrogen, and therefore does not represent truly the composition of atmospheric air. It ought to be made more clear to them that the fundamental mistake lies in using a formula which implies definite chemical composition, and the existence of a definite compound with definite properties, rather than a mere mixture of two things which are not present in fixed and invariable proportions, and, being merely mechanically mixed together, are capable of being separated by merely mechanical processes. More care should be taken by the teachers to explain the meaning and application of chemical formulæ.

Q. 12 consists of an easy problem in the calculation of weights and volume. Rather unexpectedly, this was attempted by a smaller proportion of the candidates than usual, and by them often unsuccessfully.

Attention should be drawn to the fact that there is a tendency to write symbols carelessly. Such instances as PB for Pb, MN for Mn, Co for CO, were quite common.