I50 



NATURE 



{Bee. 23, 1875 



My own early experience suggested a solution. Might I 

 not deliver some well advertised public scientific lectures of a 

 sufficiently light and sensational character to captivate the intel- 

 lect by the natural bait of wonderment ? If so, the systematic 

 classes might be fed by their means. 



My first idea was, considering the poverty of the Institute at 

 that time, to charge twopence or threepence for admission to 

 such lectures, but on communicating my scheme to Mr. Arthur 

 Ryland, the Vice-President of the Institute, he improved it 

 materially by suggesting that the charge for such lectures should 

 be one penny, and that they should be called " Penny Lectures." 



The Council assented to this, and on Jan. 22, 1856, I com- 

 menced the first course of Twelve Penny Lectures in the Lecture 

 Theatre, Cannon Street. 



The lecture theatre was crowded throughout the course, which 

 served its intended purpose of supplying an outline of the grasp 

 of Physical Science. This course was followed by others. I 

 continued them every Tuesday evening during above nine months 

 of each year until July 1863, when I left Birmingham. They 

 were always well attended but with some degree of fluctuation. 

 The smallest attendance was during a course on the Birmingham 

 manufactures, and the best attendance when subjects connected 

 with combustion, electricity, or my own travelling experiences 

 were treated and well illustrated. 



I do not at all presume to describe these lectures as nearly 

 equal to the Manchester lectures that have been lately delivered. 

 They were necessarily extemporised, as may be supposed from the 

 fact that, with the exception of an occasional volunteer (four or 

 five lectures per annum), I delivered them all myself, and at the 

 same time conducted the Lectures on Chemistry, Experimental 

 Physics, Junior and Ladies' Classes, and the Practical Analytical 

 Class in the Laboratory, besides being compelled to supplement 

 my very small salary by writing newspaper articles. 



I mention this to show how much may be done by small means. 

 The Institute was so poor at its beginning that I was obliged to 

 fit the lectures to the small stock of apparatus we possessed, and 

 lecture on whatever subjects I could best illustrate. The average 

 outlay upon illustrating these early lectures did not exceed three 

 or four shillings each. 



Nevertheless their object was fulfilled. The Penny Lectures 

 fed the Science Classes, which without such aliment would have 

 been starved and extinguished in their infancy. Their success 

 led to the establishment of the " Penny Readings " of the Mid- 

 land Institute in 1857 or 1858, which were, I believe, the first 

 of these entertainments that have since become so popular and 

 so much degenerated. These again were followed by the Penny 

 Arithmetic Classes and the other Penny Classes which have since 

 formed one of the leading and most important features of good 

 work done and doing in Binningham. 



The egotism of the above narrative will possibly be pardoned, 

 seeing that the experiences of the early struggles of the Science 

 Classes of the Midland Institute have been so often repeated 

 where similar efforts have been made, and are likely to be 

 continued so long as the prevailing inefficiency or total absence 

 of scientific instruction in our primary schools remains. The 

 success of these Penny Lectures, in spite of all their shortcomings, 

 in creating a demand for more thorough instruction indicates an 

 available means of rendering science classes successful in other 

 places. My advice to all concerned in the promotion of such 

 classes is that they should make no compromise in reference to 

 the classes themselves, by attempting to bring in them the sub- 

 jects down to the level of present requirements of the majority, 

 but that instead of this, they should, by means of very 

 popular, attractive, aye, even sensational public penny lectures, 

 excite curiosity, and create an interest in science among those they 

 desire ultimately to teach. 



Being now in the confessional I may as well admit that I 

 practised several small illegitimate devices to keep my audiences 

 together, one especially copied from the young lady who occu- 

 pied "the thousand and one nights," that of leading the subject 

 up to some amusing experiment just at the end of the lecture, 

 and then discovering that it was time to conclude, and therefore 

 that the experiment must be shown next Tuesday. The small 

 boys who occupied the front seats and applauded all the ex- 

 plosions soon found me out, but they came next week neverthe- 

 less, and some of these who at first were blue-fire pupils only, 

 ultimately joined the classes and became satisfactory students. 

 Therefore the Penny Lecturer should not be too rigidly regardful 

 of his own scientific dignity, but Barnumise to some extent, when 

 he can thereby advance towards the high object he seeks to 

 attain. 



" Should this meet the eye " of any disconsolate projector and 

 manager of a failing Mechanics' Institution or similar cflfort, let 

 him try Penny Lectures forthwith, not musical or dramatic 

 lectures, but lectures on the most wonderful of natural pheno- 

 mena, including as much scientific explanation as the audience 

 can digest, and at the same time let him prepare to supply the 

 solid class instruction for which such lectures should ultimately 

 create a demand. W. Mattieu Williams 



Belmont, Twickenham 



Proposed Optical Barometer 



I WAS led the other day to consider the possible effect of 

 changes of barometric pressure on the ultimate destination of 

 light passing through lighthouse refracting agents, and although 

 I was satisfied that such changes cannot produce any effects of 

 practical importance, the idea occurred to me that a glass prism 

 might be used as a barometer. When a refracting prism is suc- 

 cessively immersed in media of different refractive indices the 

 ultimate angular deviation of the ray will, as is well known, 

 depend in each case on the relative indices of the glass and the 

 medium surrounding it at the time of the experiment. And as 

 the refractive index of atmospheric air varies with its density, the 

 amount of deviation of the refracted ray will be a measure of the 

 density of the air, i.e. will give the means of ascertaining the 

 reading of the barometer at the time. 



If the ray of light were made to pass through a number of 

 refracting and totally reflecting prisms the deviation would be 

 increased. If with these prisms a microscope were combined 

 the prisms might be used as a barometer. Or if the ray be 

 received obliquely on a number of pieces of glass having parallel 

 faces and slightly separated from each other, although there 

 would be no angular deviation there would be horizontal dis- 

 placement which would admit of being measured by a micro- 

 meter. How far such an application would be of practical value- 

 is certainly doubtful, as the effects of changes of temperature on 

 the prism itself might interfere with the very limited range of the 

 instrument. Or again, it is possible that easterly, westerly, or 

 other currents — or perhaps differences in the hygrometric state of 

 the atmosphere — may affect the index of refraction otherwise 

 than by the mere changes of density which they produce. But 

 if such be the case, the refracting prism will be useful in deter- 

 mining the existence and amount of such variations in the re- 

 frangibility of the atmosphere. 



Edinburgh, Dec. 13 Thomas Stevenson 



Seasonal Colour in Flow^ers 



The "blue of the wild hyacinth" (see vol. xiii. p. 129) is 

 anticipated by the yellow of the primrose, the daffodil, the 

 marsh marigold, the coltsfoot, the lesser celandine {Ranunculus 

 Ficaria), and especially the winter aconite. We may add as 

 contemporaries the buttercup, the yellow deadnettle, and the 

 cowslip. The furze blooms in autumn and winter, and the 

 golden broom in spring ; the dandelion and the groundsel flower 

 during the greater part of the year. The "deep scarlet of 

 our summer flowers," represented in Britain by the poppies 

 and the pimpernel only, is accompanied by the no less vivid 

 blue of the cornflower, the wild chicory, the viper's bugloss 

 {Echium), whose blossoms change from red to blue as they 

 approach maturity, the flax, and the various campanulas. I say 

 nothing of white flowers ; but it is worth notice that the hepa- 

 tica, bugle {Ajuga), and milkwort {Polygala), vary to almost 

 precisely the same shades of blue, white, and pink, at quite 

 different seasons. ' R. A. Pryor 



Hatfield, Dec. 17 



Glands of the Cherry Laurel 

 The nectariferous glands on the back of the leaf of the cherry 

 laurel (vol. xiiL p. 107) are present also, I believe, in all the 

 Drupacese. The position is not in all cases the same ; but 

 when the glands are not found on the back of the leaf, they 

 may be seen on the petiole. Ants may often be found drinking 

 this leaf-honey ; and I heard, two or three years ago, that the 

 same attraction had brought many hive-bees to the laurels in a 

 garden at Sidmouth. E. H. 



OUR ASTRONOMICAL COLUMN 

 Variable Stars.— Nos. 2065-67 of the "Astrono- 

 mische Nachrichten " contain another of Prof. Schonfeld's 



