Is not

have an immense circulation to be remunerative. this one among many signs that the untrammelled Americans are rapidly outstripping us in the love for and the spread of scientific knowledge? It is certainly a noteworthy phenomenon which we wish could be witnessed nearer home. The editorial preface to the series concludes thus :-" If in the ulterior object of his (Professor Tyndall's) labours, the awakening of a spirit of scientific inquiry among our young thinkers, and the fostering of this tendency by liberal endowments from our wealthier citizens, his success shall be ultimately apparent, our whole country will have reason to thank the eminent Englishman." The following are a few passages from his concluding lecture :

"It is never to be forgotten that not one of those great investigators, from Aristotle down to Stokes and Kirchhoff, had any practical end in view, according to the ordinary definition of the word 'practical.' They did not propose to themselves money as an end, and knowledge as a means of obtaining it. For the most part, they nobly reversed this process, made knowledge of their end, and such money as they possessed the means of obtaining it. We may see to-day the issues of their work in a thousand practical forms, and this may be thought sufficient to justify it, if not ennoble their efforts. But they did not work for such issues; their reward was of a totally different kind. In what way different? We love clothes, we love food, we love fine equipages, we love money, and any man who can point to these as the results of his efforts in life justifies these efforts before all the world. In America and England more especially he is a practical man. But I would appeal confidently to this assembly whether such things exhaust the demands of human nature? Given clothes, given food, given carriages, given money is there no pleasure beyond what these can cover which the possessor of them would still covet? The very presence here for six inclement nights of this audience, embodying, I am told, to a great extent, the mental force and refinement of this city, is an answer to my question. I need not tell such an assembly that there are joys of the intellect as well as joys of the body, or that these pleasures of the spirit constituted the reward of our great investigators. Led on by the whisperings of natural truth, through pain and self-denial, they often pursued their work. With the ruling passion strong in death, some of them, when no longer able to hold a pen, dictated to their friends the results of their labours, and then rested from them for ever. . . . That scientific discovery may put not only dollars into the pockets of individuals, but millions into the exchequers of nations, the history of science amply proves; but the hope of its doing so is not the motive power of the investigator. It never can be his motive power.

"When analysed, what are industrial America and industrial England? If you can tolerate freedom of speech on my part, I will answer this question by an illustration. Strip a strong arm, and regard the knotted muscles when the hand is clinched and the arm bent. Is this exhibition of energy the work of the muscle alone? By no means. The muscle is the channel of an influence, without which it would be as powerless as a lump of plastic dough. It is the delicate unseen nerve that unlocks the power of the muscle. And without those filaments of genius which have been shot like nerves through the body of society by the original discoverers, industrial America and industrial England would, I tear, be very much in the condition of that plastic dough. At the present time there is a cry in England for technical education, and it is the expression of a true national want; but there is no outcry for original investigation. Still without this, as surely as the stream dwindles when the spring dries, so surely will their technical education lose all force of growth, all power of reproduction. Our great investigators have given us sufficient work for a time;

but if their spirit die out, we shall find ourselves eventually in the condition of those Chinese mentioned by De Tocqueville, who, having forgotten the scientific origin of what they did, were at length compelled to copy without variation the inventions of an ancestry who, wiser than themselves, had drawn their inspiration direct from Nature.

"To keep society as regards science in healthy play, three classes of workers are necessary: Firstly, the investigator of natural truth, whose vocation it is to pursue that truth, and extend the field of discovery for the truth's own sake, and without any reference to practical ends. Secondly, the teacher of natural truth, whose vocation it is to give public diffusion to the knowledge already won by the discoverer. Thirdly, the applier of natural truth, whose vocation it is to make scientific knowledge available for the needs, comforts, and luxuries of life. These three classes ought to coexist, and interact upon each other. Now, the popular notion of science, both in this country and in England, often relates, not to science strictly so called, but to the applications of science. Such applications, especially on this continent, are so astounding they spread themselves so largely and umbrageously before the public eye-as to shut out from view those workers who are engaged in the profounder business of discovery."

After quoting De Tocqueville on the supposed unfavourable influence which republicanism has on the advance of science, Prof. Tyndall says:

I

"It rests with you to prove whether these things are necessarily so, whether the highest scientific genius cannot find in the midst of you a tranquil home. should be loth to gainsay so keen an observer and so profound a critical writer, but, since my arrival in this country, I have been unable to see anything in the constitution of society to prevent any student with the root of the matter in him from bestowing the most steadfast devotion on pure science. If great scientific results are not achieved in America, it is not to the small agitations of society that I should be disposed to ascribe the defect, but to the fact that men among you who possess the genius for scientific inquiry are laden with duties of administration or tuition so heavy as to be utterly incompatible with the continuous or tranquil meditation which original investigation demands. I do not think this state of things likely to last. I have seen in America willingness on the part of individuals to devote their fortunes in the matter of education to the service of the commonwealth, for which I cannot find a parallel elsewhere.

"This willingness of private men to devote fortunes to public purposes requires but wise direction to enable you to render null and void the prediction of De Tocqueville. Your most difficult problem will be not to build institutions, but to make men; not to form the body, but to find the spiritual embers which shall kindle within that body a living soul. You have scientific genius among you; not sown broadcast, believe me, but still scattered here and there. Take all unnecessary impediments out of its way. You have asked me to give these lectures, and I cannot turn them to better account than by asking you in turn to remember that the lecturer is usually the distributor of intellectual wealth amassed by better men. It is not as lecturers, but as discoverers, that you ought to employ your highest men. Keep your sympathetic eye upon the originator of knowledge. Give him the freedom necessary for his researches, not overloading him either with the duties of tuition or of administration, not demanding from him so-called practical results-above all things, avoiding that question which ignorance so often addresses to genius: What is the ue of your work?' Let him make truth his object, however impracticable for the time being, that truth may appear. If you cast your bread thus upon the waters, then be assured it will return to you, though it may after many days."

be

objects, such as the sun and stars, comets, nebulæ, planets, and so on; we must for this purpose have something attached to the telescope. Fig. 16 shows a star spectroscope, which differs in arrangement only and not in principle from other spectroscopes, except in one point to which I have to draw attention with regard to this spectroscope. I have insisted on the importance of the slit; but you will see in a moment that the image of a star, if it is a good image, will be a mere point in the telescope, and therefore, while

P

FIG. 17.-Direct-vision prism with three prisms.

a slit is not absolutely necessary, it is essential to have some arrangement by which that point of light, the spectrum of which would be merely a line, and therefore not broad enough to enable us to see what the lines are which we may expect in the spectra of stars, if they be anything like the spectrum of the sun, shall be turned into a band. That has been accomplished by means of a

cylindrical lens, its function being to leave the light alone in one direction, but to turn it into a band in another direction, so that when the light of the star gets through such a lens, it is no longer a point but a line, and this is then grasped by the collimating lens, sent through the prisms, and received by the observing telescope, so that when you get the image of it in the observing telescope, instead of having a line of light so fine that the lines in it cannot be distinguished, it is a distinctly broad band in which the lines can be observed. As this lens is simply a contrivance for enabling the eye to see about where there is a line, I submit now, as I submitted some years ago, that a proper place for it is close to the eye, between the eye and the image. I have been gratified to find that, in many of the spectroscopes used on the Continent, this arrangement is adopted.

We have now an idea of the action of the simple prism. I will next bring to your notice another kind of prism, which differs from the simple one very much as the achromatic telescope differs from the non-achromatic one, which was the first attempt made at an instrument for astronomical observations. Many of you know that the object-glass of a telescope, as now constructed, consists of two lenses made of different kinds of glass. Of course, we have dispersion and deviation at work in both these kinds of glass, but the lenses are so arranged, and their curves are so chosen, that, as a total result, the deviation is kept while the dispersion is eliminated, so that, in the telescope, we have a nearly white image of anything which

gives us ordinary light, although, as you know, it is by the deviation alone that we are enabled to get the magnified image of that object. So also in the spectroscope we have an opportunity of varying the deviation and the dispersion. By a converse arrangement we can keep the dispersion while we lose the deviation; in other words, we have what is called a direct-vision spectroscope. If we take one composed of two prisms of one kind of glass which possesses a considerable refractive power, and three prisms of another kind which does not refract so strongly, arranged with their bases the opposite way, the deviation caused by the two prisms in the one direction will be neutralised by the deviation of the three prisms in the opposite direction; whilst the dispersion by the three prisms, exceeds that which is caused by the two prisms in the opposite direction, the latter dispersion therefore will neutralise a portion only of the dispersion due to the three prisms. The final result is that there is an outstanding dispersion after the deviation has been neutralised, so that when we want to examine the spectrum of an object we no longer have to look at it at an angle. No doubt you recollect the angle that was made by the light the moment it left the prism, but we have an opportunity, by this arrangement, of seeing the spectrum of an object by looking straight at the source of light in the application of spectrum analysis, especially to the microscope and telescope, this modification due to M. Janssen, the well-known astronomer, who was the first to bring it into general notice-is one of great practical importance, so that in any research which does not require excessive dispersion,

this direct-vision arrangement is getting into common use. I have here another direct-vision arrangement which is well worthy of being brought to your notice. It does not depend at all upon the principles I have just been trying to explain to you. It is called the Herschel-Browning direct-vision spectroscope, in which the ray is refracted and reflected internally, in the prisms themselves. We have therefore, in addition to the simple prism which I formerly brought to your attention, two other aids to research of extreme value in certain classes of observations. The direct-vision spectroscopes which are now sold are made on one of the two principles just described; some of them are made so small that they can be easily carried in the waistcoat-pocket, and still are so powerful that all the principal, and many of the less prominent, lines in the solar spectrum may be seen with them.

Of the special application of the spectroscope to the microscope I need say but little now. The spectroscope thus used is a direct-vision one, this form being far more convenient for attaching to the microscope. The light which illuminated the object in the microscope was first of all passed through a prism; but in later arrangements it passes through the prism in its passage from the object. This is obviously a much better plan, because, in the first instance, you could only deal with transparent objects; but here, as you deal in any case with the light that comes from the object itself, it is quite immaterial whether the object be opaque or transparent. J. NORMAN LOCKYER (To be continued.)

SCHOLARSHIPS AND EXAMINATIONS FOR NATURAL SCIENCE AT CAMBRIDGE, 1873 THE following is a list of the Scholarships and Exhibitions for proficiency in Natural Science to be offered at the several Colleges in Cambridge during the

present year :

TRINITY COLLEGE.-One or two of the value of about 80l. per annum. The examination will be on April 5, and will be open to all Undergraduates of Cambridge and Oxford, and to persons under twenty who are not members of the Universities. Further information may be obtained from the Rev. E. Blore, Tutor of Trinity College.

ST. JOHN'S COLLEGE.-One of the value of 50l. per annum. The examination (in Chemistry, Physics, and Physiology, with Geology, Anatomy, and Botany) will be in December, and will be open to all persons who have not entered at the University, as well as to all who have entered and have not completed one term of residence. Natural Science is made one of the subjects of the annual college examination of its students at the end of the academical year, in May; and exhibitions and foundation scholarships will be awarded to students who show an amount of knowledge equivalent to that which in classics or mathematics usually gains an exhibition or scholarship in the college. In short Natural Science is on the same footing with Classics and Mathematics, both as regards teaching

and rewards.

CHRIST'S COLLEGE.-One or more, in value from 30. to 70l. according to the number and merits of the candidates, tenable for three-and-a-half years, and for three years longer by those who reside during that period at the College. The examination will be on April 1, and will be open to the undergraduates of the College; to non-collegiate undergraduates of Cambridge; to all undergraduates of Oxford; and to any students who are not members of either University. The candidates may select their own subjects for examination. There are other Exhibitions which are distributed annually among the most deserving students of the College. Further information may be obtained from John Peile, Esq., Tutor of the College.

CAIUS COLLEGE.-One of the value of 60l. per annum. The examination will be on April 1, in Chemistry and Experimental Physics, Zoology, with Comparative Anatomy, Physiology, and Botany, with Vegetable Anatomy and Physiology; it will be open to students who have not commenced residence in the University. There is no limitation as to age.-Scholarships of the value of 201. each, or more if the candidates are unusually good, are offered, for Anatomy and Physiology, to members of the college.-Gentlemen elected to the Tancred Medical Studentships are required to enter at this College; these Studentships are four in number, and the annual value of each is 113. Information respecting these may be obtained from B. J. L. Frere, Esq., 28, Lincoln's Inn Fields, London.

CLARE COLLEGE.-One of the value of 50%. per annum, tenable for 3 years. The examination (in Chemistry, Chemical Physics, Comparative Anatomy, and Physiology, and Geology) will be on March 26, and will be open to students intending to begin residence in October.

DOWNING COLLEGE.-Ōne or more of the value of 40%. per annum. The examination (in Chemistry, Comparative Anatomy, and Physiology) will be early in April, and will be open to all students not members of the University, as well as all undergraduates in their first term.

SIDNEY COLLEGE.-Two of the value of 40%. per annum. The examination (in Heat, Electricity, Chemistry, Geology, Zoology and Physiology, and Botany), will be on April 1, and will be open to all students who intend to commence residence in October.

EMMANUEL COLLEGE.-One or more of the value of 50l. tenable for two years. The examination on April 1

will be open to students who have not commenced residence.

PEMBROKE COLLEGE.-One or more of the value of 20l. to 60l. according to merit. The examination (in June, in Chemistry. Physics, and other subjects) will be open to students under twenty years of age.

ST. PETER'S COLLEGE.-One from 50l. to 80l. per annum, according to merit. The examination, date not yet fixed, in Chemistry, Comparative Anatomy and Physiology, and Botany, will be open to students who will be under twenty-one years of age on October 1, 1873, and who have not commenced residence.

annum.

KING'S COLLEGE.-One of the value of about 80l. per The examination, on April 21, will be open to all candidates under twenty, and to undergraduates of the College in their first and second year. There will be an examination in elementary classics and mathematics, in addition to three or more papers in Natural Science, including Physics, Chemistry, and Physiology.

Although several subjects for examination are in each instance given, this is rather to afford the option of one or more to the candidates than to induce them to present a superficial knowledge of several. Indeed, it is expressly stated by some of the colleges that good clear knowledge of one or two subjects will be more esteemed than a general knowledge of several.

the University, will, in most instances, be required to Candidates, especially those who are not members of show a fair knowledge of classics and mathematics, such, for example, as would enable them to pass the previous Examination.

There is no restriction en the ground of religious denomination in the case of these or of any of the Scholarships or Exhibitions in the colleges or in the University.

Further information may be cbtained from the Tutors of the respective Colleges.

It may be added that Trinity College will give a Fellowship for Natural Science once, at least, in three years: and that most of the Colleges are understood to be willing to award Fellowships for merit in Natural Science equivalent to that for which they are in the habit of giving them for Classics and Ma'hematics.

NOTES ON ZOOLOGY AND BOTANY IN

LISBON

L' ISBON possesses a remarkable natural history collection which is at present in process of transference to the new Polytechnic School buildings, which are only just completed. This institution is of imposing dimensions, built in the form of a square, with a quadrangular garden in the centre, and contain spacious and welllighted laboratories, lecture rooms, and galleries for museum purposes. On the ground floor is a mineralogical and palæontological collection, and over this is the natural history series, which is contained in four fine rooms, one of which is devoted entirely to the African fauna, in which the museum is particularly rich. In all the rooms table cases are placed down the central line containing the collection of shells, which is very fine and well arranged, whilst upright cases are ranged along the walls and are filled with stuffed Mammalia, and birds, and variously preserved reptiles and fish. Amongst the Mammalia are two manatees, a fine specimen of the Aye-Aye, Cheiromys, and also one of the curious little otter-like animals from Africa, Potamogale velox, which has its tail flattened out into a vertical rudder. These are mentioned as rarities. The series is large and especially good in insectivora, moles, shrews, &c.

The birds are quite remarkable for the excellence of their preservation, and as the series is very extensive, it forms the chief feature of the collection. There are a large