March 5, 1885] 



NA TURE 



409 



the friction of the mercury are avoided by connecting the vessels 

 by wires with the earth. 



If H and I form a mass of lead, I infer that three interchanges 

 of D and E will be required, so that each weight shall be brought 

 opposite the top and bottom of each mass to eliminate want of 

 homogeneity in the lead. In the plan I propose only one inter- 

 change will be needed. 



The effect, if any, of the vessels full of mercury being at 



unequal distances from the arms of the balance can be readily 

 determined and allowed for. 



The plan I suggest may have already presented itself to the 

 eminent scientists who have originated their notable improve- 

 ment on Von Jolly's plan. The pleasure I had in reading the 

 account of their proposed research has prompted me to make 

 these suggestions. Alfred M. Mayer 



Stevens Institute of Technology, Hoboken, New Jersey, 

 February 7 



Bees and Flowers 



AS there is a prevailing idea that bees prefer red and blue to 

 other colours, the f :>llowing observations on their habits may be 

 of interest : — The common hive bees were very busy among the 

 flowers in the garden this morning. Those most frequented 

 were yellow crocus, snowdrop, and Christmas rose. Next in 

 order, winter aconite, yellow jessamine, and blue scilla. On 

 sweet blue violets and on a dwarf erica, which is now flowering, 

 I could see none. Hitherto my observations led me to suppose 

 they never visited the blue scilla for honey, as I had never seen 

 them settle down to it in a business-like manner, but simply flit 

 over it and go to something else. G. W. Bulman 



Corbridge-on- Lyne 



Free Lectures 

 RVED in Nature for February 19 (p. 367) a reference 

 to the free lectures at Liverpool, and the inquiry, Why cannot 

 the same thing be done in other large towns? It may interest 

 your readers to learn that a series of free lectures has been given 

 during the past two winters by the professors of this College. 

 Tickets for these lectures are distributed through the agency of 

 a committee composed partly of employers, and the attendance 

 at each lecture numbers between 600 and 700. The audience 

 consists wholly of persons in receipt of weekly wages, the ser- 

 vices of the lecturers are given gratuitously, and no charge 

 whatever is made for admission. The small expenses of printing 

 ng programmes and tickets are defrayed by the Com- 

 mittee. I inclose the syllabus of this, the second year's course, 

 now drawing to a conclu-ion. 



In addition to these lectures we have from time to time free lec- 

 tures by gentlemen possessing special knowledge of the contents of 

 the Free Libraries. These, too, are attended by a large number, 

 chiefly of working people, and when the art galleries are com- 

 pleted next year arrangements of a similar kind will doubtless 

 be made in connection with them. William A. Tilden 



The Mason Science College, Birmingham, February 24 



A Tracing Paper Screen 

 I CAN add to the testimony of Mr. Charles Taylor about the 

 efficiency of a screen of tracing paper. I have used for several 

 years a small screen of tracing cloth mounted on rollers like a 

 map. It is very portable and soo 1 fixed. With a sciopticon 

 lantern (oil lamp) I have shown transparencies in the winter 

 months to an audience of seven hundred men in a Midland 

 Railway mess-room during the breakfast hour— 8. 15 to 8.50 

 a.m. — though the windows are by no means in the best position, 



and the loom is lighted by skylights as well as by side windows. 

 It is a pity this screen is not better known and more extensively 

 used for scientific lectures. H. ARNOLD BEMROSE 



Irongate, Derby, February 28 



An Author's Gratitude 

 I wish to express my gratitude to Nature and to the 

 reviewer in Nature of my little pamphlet on Electrical 

 Units for exposing a compound error by which the farad came 

 to be described as a fraction of the electrostatic C.G.S. unit of 

 capacity instead of the electro-magnetic unit. Was there ever a 

 greater blunder ? It was as if I had said the value of the tenth 

 part of a farthing is sufficient to pay off a million times the 

 National Debt of Great Britain. On recovering from the shock 

 occasioned by the revelation, I hastened to the printer, and got 

 him to correct the error " ere the sun went down," and now I 

 overflow with gratitude to your reviewer, who has relieved me 

 of the awful incubus of an error of the IO 20 magnitude. 



Richard Wormell 



SCIENTIFIC LABORATORIES^ 



T FEEL that the present occasion, upon which you have 

 ■*■ done me the honour to ask me to preside, is one of 

 very great importance indeed, and I wish some person more 

 competent to preside on such an occasion and give a 

 suitable inaugural address were in my place. I am 

 afraid I must confine myself to something not at all 

 worthy of the greatness of an occasion which is almost 

 the opening of a new university. Not quite so, because 

 the real opening of this college took place several months 

 ago ; but still it is an occasion which I feel to be much 

 more than merely the opening of a department — a work- 

 ing department — in the college ; an occasion of so great 

 moment that I regret that I shall not be able to give any- 

 thing that could be properly considered a worthy inaugural 

 address. I shall be obliged to ask your indulgence if I 

 confine myself specially to departments with which I am 

 personally familiar — scientific laboratories. The labora- 

 tory of a scientific man is his place of work. The 

 laboratory of the geologist and of the naturalist is the face 

 of this beautiful world. The geologist's laboratory is the 

 mountain, the ravine, and the seashore. The naturalist 

 and the botanist go to foreign lands, to study the wonders 

 of nature, and describe and classify the results of their 

 observations. But they must do more than merely 

 describe, represent, and depict what they have seen. 

 They must bring home the products of their expeditions 

 to their studies, and have recourse to the appliances of 

 the laboratory properly so-called for their thorough and 

 detailed examination. The naturalist in his laboratory 

 with his microscope and appliances for the keenest exam- 

 ination, learns to know more than can be learned by 

 merely looking at external beauties. The geologist brings 

 his specimens to the chemist — is himself a chemist per- 

 haps — brings his crystals to the physical laboratory to be 

 examined as to their physical properties, their hardness, 

 the angles between their faces, their optical qualities. 

 Some people might think this an ignoble way to deal with 

 crystals. But it is not so to the trained eye and deeper 

 thought of the scientific man. The scientific man sees 

 and feels beauty as much as any mere observer — as much 

 as any artist or painter. But he also sees something 

 underlying that beauty ; he wishes to learn something of 

 the actions and forces producing those beautiful results. 

 The necessity for study below the surface seems to have 

 been earliest recognised in anatomy, and earliest carried 

 out in human anatomy. 1 am not going to speak of the 

 work of scientific research generally, but with reference to 

 the special occasion which brings us here this day — the 

 opening of the chemical and physical laboratories of the 

 University College of North Wales. I am going to speak 



by rrof. Sir William Thomson, F.R.S., on the occasion of the 

 boratories of University College, Bangor. 



