Comptes rendus

comptes rendus de patients

SUBJECT AREA: Metallurgy

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After graduating in chemistry from the Ecole Polytechnique in 1887, Charpy continued to work there on the physical chemistry of solutions for his doctorate. He joined the Laboratoire d'Artillerie de la Marine in 1892 and began to study the structure and mechanical properties of various steels in relation to their previous heat treatment. His first memoir, on the mechanical properties of steels quenched from various temperatures, was published in 1892 on the advice of Henri Le Chatelier. He joined the Compagnie de Chatillon Commentry Fourchamboult et Decazeville at their steelworks in Imphy in 1898, shortly after the discovery of Invar by G.E. Guillaume. Most of the alloys required for this investigation had been prepared at Imphy, and their laboratories were therefore well equipped with sensitive and refined dilatometric facilities. Charpy and his colleague L.Grenet utilized this technique in many of their earlier investigations, which were largely concerned with the transformation points of steel. He began to study the magnetic characteristics of silicon steels in 1902, shortly after their use as transformer laminations had first been proposed by Hadfield and his colleagues in 1900. Charpy was the first to show that the magnetic hysteresis of these alloys decreased rapidly as their grain size increased.

The first details of Charpy's pendulum impact testing machine were published in 1901, about two years before Izod read his paper to the British Association. As with Izod's machine, the energy of fracture was measured by the retardation of the pendulum. Charpy's test pieces, however, unlike those of Izod, were in the form of centrally notched beams, freely supported at each end against rigid anvils. This arrangement, it was believed, transmitted less energy to the frame of the machine and allowed the energy of fracture to be more accurately measured. In practice, however, the blow of the pendulum in the Charpy test caused visible distortion in the specimen as a whole. Both tests were still widely used in the 1990s.

In 1920 Charpy left Imphy to become Director-General of the Compagnie des Aciéries de la Marine et Homecourt. After his election to the Académie des Sciences in 1918, he came to be associated with Floris Osmond and Henri Le Chatelier as one of the founders of the "French School of Physical Metallurgy". Around the turn of the century he had contributed much to the development of the metallurgical microscope and had helped to introduce the Chatelier thermocouple into the laboratory and to industry. He also popularized the use of platinum-wound resistance furnaces for laboratory purposes. After 1920 his industrial responsibilities increased greatly, although he continued to devote much of his time to teaching at the Ecole Supérieure des Mines in Paris, and at the Ecole Polytechnique. His first book, Leçons de Chimie (1892, Paris), was written at the beginning of his career, in association with H.Gautier. His last, Notions élémentaires de sidérurgie (1946, Paris), with P.Pingault as co-author, was published posthumously.

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SUBJECT AREA: Horology, Metallurgy

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Guillaume came from a family of clock-and watchmakers. He was educated at the Gymnasium in Neuchâtel and at Zurich Polytechnic, from which he received his doctorate in 1883 for a thesis on electrolytic capacitors. In the same year he joined the International Bureau of Weights and Measures at Sèvres in France, where he was to spend the rest of his working life. He retired as Director in 1936. At the bureau he was involved in distributing the national standards of the metre to countries subscribing to the General Conference on Weights and Measures that had been held in 1889. This made him aware of the crucial effect of thermal expansion on the lengths of the standards and he was prompted to look for alternative materials that would be less costly than the platinum alloys which had been used. While studying nickel steels he made the surprising discovery that the thermal expansion of certain alloy compositions was less than that of the constituent metals. This led to the development of a steel containing about 36 per cent nickel that had a very low thermal coefficient of expansion. This alloy was subsequently named "invar", an abbreviation of invariable. It was well known that changes in temperature affected the timekeeping of clocks by altering the length of the pendulum, and various attempts had been made to overcome this defect, most notably the mercury-compensated pendulum of Graham and the gridiron pendulum of Harrison. However, an invar pendulum offered a simpler and more effective method of temperature compensation and was used almost exclusively for pendulum clocks of the highest precision.

Changes in temperature can also affect the timekeeping of watches and chronometers, but this is due mainly to changes in the elasticity or stiffness of the balance spring rather than to changes in the size of the balance itself. To compensate for this effect Guillaume developed another more complex nickel alloy, "elinvar" (elasticity invariable), whose elasticity remained almost constant with changes in temperature. This had two practical consequences: the construction of watches could be simplified (by using monometallic balances) and more accurate chronometers could be made.

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See also: Le Roy, Pierre

1) Pol., Conf. rédacteur de comptes rendus

2) Jur. procès- verbaliste

Conf. rédacteur de comptes rendus analytiques; dans le secteur privé: procès-verbaliste

dépenses (dans les comptes rendus) (RL)

casebook ['keɪsbʊk]

noun

(gen) = recueil de comptes rendus de cas; Law recueil m de jurisprudence

press [pres]

presse ⇒ 1 (a)-(e) serrement ⇒ 1 (i) appuyer (sur) ⇒ 3 (a), 3 (e), 4 (a) presser ⇒ 3 (b), 3 (c) forcer ⇒ 3 (d) faire pression ⇒ 4 (b)

1 noun

(a) (newspapers) presse f;

∎ the national/local press la presse nationale/locale;

∎ freedom of the press la liberté de la presse;

∎ they advertised in the press ils ont fait passer une annonce dans les journaux;

∎ reports in the press were biased les comptes rendus parus dans la presse étaient tendancieux;

∎ they managed to keep her name out of the press ils ont réussi à ce que son nom ne paraisse pas dans la presse

(b) (journalists) presse f;

∎ the press were there la presse était là;

∎ she's a member of the press elle a une carte de presse;

∎ ironic the gentlemen of the press ces messieurs de la presse

(c) (report, opinion) presse f;

∎ to get (a) good/bad press avoir bonne/mauvaise presse;

∎ to give sb (a) good/bad press faire l'éloge/la critique de qn

(d) (printing) presse f;

∎ to go to press (book) être mis sous presse; (newspaper) partir à l'impression;

∎ we go to press at 5 p.m. on est mis sous presse à 5 heures; (copy deadline) on boucle à 5 heures;

∎ in or at (the) press sous presse;

∎ hot or straight from the press tout frais;

∎ ready for press prêt à mettre sous presse;

∎ the proofs were passed for press on a donné le bon à tirer;

∎ prices correct at time of going to press prix corrects au moment de la mise sous presse

(e) (machine)

∎ (printing) press presse f;

∎ to set the presses rolling mettre les presses en marche; figurative mettre la machine en marche

(f) (publisher) presses fpl

(g) (for tennis racket, handicrafts, woodwork, trousers) presse f; (for cider, oil, wine) pressoir m

(h) (push)

∎ the machine dispenses hot coffee at the press of a button il suffit d'appuyer sur un bouton pour que la machine distribue du café chaud;

∎ give it a slight press appuyez légèrement là-dessus

(i) (squeeze) serrement m;

∎ he gave my hand a quick press il m'a serré la main rapidement

(j) (crowd) foule f; (rush) bousculade f; literary (of battle) mêlée f;

∎ in the press for the door we became separated dans la ruée de la foule vers la porte, nous avons été séparés;

∎ to force one's way through the press fendre la foule, se frayer un chemin à travers la foule

(k) (ironing) coup m de fer;

∎ to give sth a press donner un coup de fer à qch

(l) Irish & Scottish (cupboard) placard m, armoire f

(m) (in weightlifting) développé m

(n) (in basketball) pressing m;

∎ full court press zone-presse f (tout terrain);

∎ American figurative it was the full court press on faisait le maximum;

∎ to be engaged in a full court press to do sth faire le maximum ou tout son possible pour faire qch

(o) Industry (forming machine) presse f

(p) Military recrutement m de force

(q) Nautical

∎ press of sail or canvas pleine voilure f;

∎ under press of sail toutes voiles dehors

2 compound-forming noun

(reporter, photographer) de presse; (advertising) dans la presse

3 transitive verb

(a) (push → button, bell, trigger, accelerator) appuyer sur;

∎ try pressing it essayez d'appuyer dessus;

∎ he pressed the lid shut il a fermé le couvercle (en appuyant dessus);

∎ to press sth flat aplatir qch;

∎ to press sth home enfoncer qch;

∎ to press sth (back) into shape rendre sa forme à qch;

∎ to press one's way through a crowd/to the front se frayer un chemin à travers une foule/jusqu'au premier rang;

∎ he was pressed (up) against the railings il s'est trouvé coincé contre le grillage;

∎ I pressed myself against the wall je me suis collé contre le mur;

∎ she pressed a note into my hand elle m'a glissé un billet dans la main;

∎ he pressed his nose (up) against the window il a collé son nez à la vitre;

∎ he pressed his hat down on his head il rabattit ou enfonça son chapeau sur sa tête;

∎ she pressed the papers down into the bin elle a enfoncé les papiers dans la poubelle

(b) (squeeze → hand, arm) presser, serrer; (→ grapes, lemon, olives) presser;

∎ she pressed her son to her elle serra son fils contre elle

(c) (urge) presser, pousser; (harass) harceler, talonner;

∎ to press sb for payment/an answer presser qn de payer/répondre;

∎ she pressed me to tell her the truth elle me pressa de lui dire la vérité;

∎ if you press her she'll tell you si tu insistes, elle te le dira;

∎ if pressed, he would admit… quand on insistait ou le poussait, il admettait…;

∎ his creditors were pressing him hard ses créanciers le harcelaient ou ne lui laissaient pas le moindre répit;

∎ to be pressed for time/money être à court de temps/d'argent

(d) (force) forcer, obliger;

∎ I was pressed into signing the contract j'ai été obligé de signer le contrat;

∎ don't let yourself be pressed into going ne laissez personne vous forcer à y aller

(e) (impose, push forward → claim) appuyer, pousser; (→ opinions) insister sur;

∎ can I press a cup of tea on you? puis-je vous offrir une tasse de thé?;

∎ to press a gift on sb forcer qn à accepter un cadeau;

∎ to press (home) one's advantage profiter d'un avantage;

∎ to press one's attentions on sb poursuivre qn de ses assiduités;

∎ I don't want to press the point je ne veux pas insister;

∎ Law to press charges against sb engager des poursuites contre qn

(f) (iron → shirt, tablecloth) repasser

(g) (manufacture in mould → component) mouler; (→ record) presser

(h) (preserve by pressing → flower) presser, faire sécher (dans un livre ou un pressoir)

(i) (in weightlifting) soulever

(j) Military (enlist by force) recruter ou enrôler de force;

∎ figurative to press into service réquisitionner;

∎ the local mechanic was pressed into service le mécanicien du coin fut réquisitionné pour la circonstance

4 intransitive verb

(a) (push) appuyer;

∎ press here appuyez ou pressez ici;

∎ he pressed (down) on the accelerator il appuya sur l'accélérateur;

∎ the crowd pressed against the barriers/round the President la foule se pressait contre les barrières/autour du président;

∎ they pressed forward to get a better view ils poussaient pour essayer de mieux voir;

∎ to press through a crowd se frayer un chemin à travers une foule;

∎ to press close against sb se serrer contre qn

(b) (weight, burden) faire pression (on sur); (troubles) peser (on à);

∎ the rucksack pressed on his shoulders le sac à dos pesait sur ses épaules;

∎ her problems pressed on her mind ses problèmes lui pesaient;

∎ time presses! le temps presse!

(c) (insist)

∎ he pressed hard to get the grant il a fait des pieds et des mains pour obtenir la bourse;

∎ to press for an answer insister pour avoir une réponse immédiate;

∎ to press for an adjournment/the law to be tightened up exiger un ajournement/que la loi soit renforcée

(d) (iron) se repasser;

∎ some shirts press easily il y a des chemises qui se repassent facilement

►► press agency agence f de presse;

press agent attaché(e) m,f de presse;

British the Press Association = la principale agence de presse britannique;

press attaché attaché(e) m,f de presse;

press badge macaron m de presse;

press baron magnat m de la presse;

press box tribune f de (la) presse;

press button bouton-poussoir m;

press campaign campagne f de presse;

press card carte f de presse ou de journaliste;

press clipping coupure f de presse or de journal;

British the Press Complaints Commission = organisme britannique de contrôle de la presse;

press conference conférence f de presse;

press copy (of book) exemplaire m de service de presse;

press corps journalistes mpl;

∎ the White House press corps = les journalistes accrédités à la Maison-Blanche;

British the Press Council = organisme indépendant veillant au respect de la déontologie dans la presse britannique;

press coverage couverture-presse f;

∎ the resignation got a lot of press coverage la démission a été largement couverte dans la presse;

British press cutting coupure f de presse ou de journal;

∎ a collection of press cuttings une collection de coupures de journaux, un dossier de presse;

press gallery tribune f de (la) presse;

press handout communiqué m de presse;

press insert encart m presse;

press kit dossier m de presse (distribué aux journalistes);

press lord magnat m de la presse;

press office service m de presse;

press officer responsable mf des relations avec la presse;

press pack dossier m de presse;

press pass carte f de presse;

Typography press proof tierce f;

press relations relations fpl presse;

press release communiqué m de presse;

press report reportage m;

∎ press reports of the incident were inaccurate les articles de presse relatant l'incident étaient inexacts;

press run tirage m;

Politics press secretary ≃ porte-parole m inv du gouvernement;

British press stud bouton-pression m, pression f

➲ press ahead = press on

➲ press down

1 separable transitive verb

appuyer sur; (with force) enfoncer

2 intransitive verb

∎ to press down on sb peser sur qn

➲ press for inseparable transitive verb

(demand) exiger, réclamer;

∎ they pressed for a pay rise ils ont réclamé ou exigé une augmentation de salaire;

∎ the residents are pressing for a pedestrian zone les résidents font pression pour obtenir une zone piétonnière;

∎ the opposition are pressing for an enquiry l'opposition exige une enquête ou insiste pour que l'on fasse une enquête

➲ press in separable transitive verb

enfoncer

➲ press on intransitive verb

(continue → on journey) poursuivre ou continuer son chemin; (→ with activity) continuer; (persevere → in enterprise, job) poursuivre, persévérer;

∎ the travellers pressed on in the darkness les voyageurs poursuivirent leur chemin dans la nuit;

∎ we must press on to York or as far as York il faut poursuivre jusqu'à York;

∎ we pressed on regardless nous avons continué malgré tout

➲ press on with inseparable transitive verb

(job, negotiations) continuer, poursuivre;

∎ they pressed on with the plan in spite of opposition ils ont poursuivi leur projet malgré l'opposition rencontrée

➲ press out separable transitive verb

(a) (juice etc) exprimer

(b) Technology (holes) percer; (shapes, parts) découper

wildly ['waɪldlɪ]

adverb

(a) (violently) violemment, furieusement;

∎ waves beat wildly against the rocks les vagues venaient se heurter furieusement contre les rochers;

∎ she struggled wildly to free herself elle se débattait furieusement pour tenter de se libérer

(b) (enthusiastically) frénétiquement;

∎ the crowd applauded wildly la foule applaudissait frénétiquement

(c) (randomly) au hasard;

∎ "you're a Scorpio, aren't you" I said, guessing wildly "tu es Scorpion, non?" ai-je demandé au hasard;

∎ to swing wildly at sb/sth lancer le poing au hasard en direction de qn/qch;

∎ he dashed about wildly il s'agitait frénétiquement;

∎ exchange rates fluctuated wildly les taux de change fluctuaient de façon aberrante

(d) (extremely) excessivement;

∎ the reports are wildly inaccurate les comptes rendus sont complètement faux;

∎ to be wildly excited être surexcité;

∎ wildly expensive follement cher;

∎ he is wildly funny! il est d'un drôle!;

∎ his stories are wildly funny ses histoires sont à mourir de rire;

∎ to be wildly jealous/happy être fou de jalousie/de bonheur;

∎ I'm not wildly happy about the decision cette décision ne m'enchante pas spécialement;

∎ it's not wildly encouraging ça n'est pas franchement encourageant;

∎ I'm not wildly enthusiastic about it je ne suis pas franchement emballé

(e) (recklessly) avec témérité;

∎ he talked wildly of joining the foreign legion il parlait avec témérité de s'engager dans la légion étrangère

SUBJECT AREA: Medical technology

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After studies at colleges in Limoges and later in Paris, Arsonval became a doctor of medicine in 1877. In 1882 the Collège de France established a laboratory of biophysics with Arsonval as Director, and he was Professor from 1894.

His most outstanding scientific contributions were in the field of biological applications of electricity. His interest in muscle currents led to a series of inventions to assist in research, including the moving-coil galvanometer. In 1881 he made a significant improvement to the galvanometer by reversing the magnetic elements. It had been usual to suspend a compass needle in the centre of a large, stationary coil, but Arsonval's invention was to suspend a small, light coil between the poles of a powerful fixed magnet. This simple arrangement was independent of the earth's magnetic field and insensitive to vibration. A great increase in sensitivity was achieved by attaching a mirror to the coil in order to reflect a spot of light. For bacterial-research purposes he designed the first constant-temperature incubator controlled by electricity. His experiments on the effects of high-frequency, low-voltage alternating currents on animals led to the first high-frequency heat-therapy unit being established in 1892, and later to methods of physiotherapy becoming a professional discipline.

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SUBJECT AREA: Photography, film and optics

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Educated as a notary's clerk, Bayard began his working life in Paris in the Ministry of Finance. His interest in art led him to investigations into the chemical action of light, and he began his experiments in 1837. In May 1839 Bayard described an original photographic process which produced direct positive images on paper. It was devised independently of Talbot and before details of Daguerre's process had been published. During the same period, similar techniques were announced by other investigators and Bayard became involved in a series of priority disputes. Bayard's photographs were well received when first exhibited, and examples survive to the present day. Because the process required long exposure times it was rarely practised, but Bayard is generally credited with being an independent inventor of photography.

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SUBJECT AREA: Broadcasting, Electronics and information technology, Telecommunications

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Branly received his education at the Lycée de Saint Quentin in the Département de l'Aisne and at the Henri IV College of Paris University, where he became a Fellow of the University, graduating as a Doctor of Physics in 1873. That year he was appointed a professor at the College of Bourges and Director of Physics Instruction at the Sorbonne. Three years later he moved to the Free School in Paris as Professor of Advanced Studies. In addition to these responsibilities, he qualified as an MD in 1882 and practised medicine from 1896 to 1916. Whilst carrying out experiments with Hertzian (radio) waves in 1890, Branly discovered that a tube of iron filings connected to a source of direct voltage only became conductive when the radio waves were present. This early form of rectifier, which he called a coherer and which needed regular tapping to maintain its response, was used to operate a relay when the waves were turned on and off by Morse signals, thus providing the first practical radio communication.

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See also: Hertz, Heinrich Rudolph; Marconi, Marchese Guglielmo

SUBJECT AREA: Electricity

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After technical training at the Ecole des Arts et Métiers at Aix, Faure was employed superintending the erection of factories in France and England. These included the Cotton Powder Company plant in Faversham for the manufacture of the explosive Tonite invented by Faure. He also invented distress signals used by the merchant navy. It was between 1878 and 1880 that he performed his most important work, the improvement of the Planté cell. Faure's invention of coating the lead plates with a paste of lead oxide substantially reduced the time taken to form the plates. Their construction was subsequently further improved by Swan and others. These developments appeared at a particularly opportune time because lead-acid secondary cells found immediate application in telegraphy and later in electric lighting and traction systems, where their use resulted in reduced costs of providing supplies during peak-load periods. In his later years Faure's attention was directed to other electrochemical problems, including the manufacture of aluminium.

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SUBJECT AREA: Mining and extraction technology

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While attending the drilling of artesian wells in southern France in 1833, Fauvelle noticed that the debris from the borehole was carried out by the ascending water. This observation caused him to conceive the idea that the boring process need not necessarily be interrupted in order to clear the hole with an auger. It took him eleven years to develop his idea and to find financial backing to carry out his project in practice. In 1844, within a period of fifty-four days, he secretly bored an artesian well 219 m (718 ft) deep in Perpignan. One year later he secured his invention with a patent in France, and with another the following year in Spain.

Fauvelle's process involved water being forced by a pressure pump through hollow rods to the bottom of the drill, whence it ascended through the annular space between the rod and the wall of the borehole, thus flushing the mud up to the surface. This method was similar to that of Robert Beart who had secured a patent in Britain but had not put it into practice. Although Fauvelle was not primarily concerned with the rotating action of the drill, his hydraulic boring method and its subsequent developments by his stepson, Alphonse de Basterot, formed an important step towards modern rotary drilling, which began with the work of Anthony F. Lucas near Beaumont, Texas, at the turn of the twentieth century. In the 1870s Albert Fauck, who also contributed important developments to the structure of boring rigs, had combined Fauvelle's hydraulic system with core-boring in the United States.

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See also: Crælius, Per Anton

SUBJECT AREA: Electricity, Public utilities

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Gramme trained as a carpenter and showed an early talent for working with machinery. Moving to Paris he found employment in the Alliance factory as a model maker. With a growing interest in electricity he left to become an instrument maker with Heinrich Daniel Rühmkorff. In 1870 he patented the uniformly wound ring-armature dynamo with which his name is associated. Together with Hippolyte Fontaine, in 1871 Gramme opened a factory to manufacture his dynamos. They rapidly became a commercial success for both arc lighting and electrochemical purposes, international publicity being achieved at exhibitions in Vienna, Paris and Philadelphia. It was the realization that a Gramme machine was capable of running as a motor, i.e. the reversibility of function, that illustrated the entire concept of power transmission by electricity. This was first publicly demonstrated in 1873. In 1874 Gramme reduced the size and increased the efficiency of his generators by relying completely on the principle of self-excitation. It was the first practical machine in which were combined the features of continuity of commutation, self-excitation, good lamination of the armature core and a reasonably good magnetic circuit. This dynamo, together with the self-regulating arc lamps then available, made possible the innumerable electric-lighting schemes that followed. These were of the greatest importance in demonstrating that electric lighting was a practical and economic means of illumination. Gramme also designed an alternator to operate Jablochkoff candles. For some years he took an active part in the operations of the Société Gramme and also experimented in his own workshop without collaboration, but made no further contribution to electrical technology.

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SUBJECT AREA: Medical technology, Photography, film and optics

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At the age of 19 Marey went to Paris to study medicine, becoming particularly interested in the problems of the circulation of the blood. In an early communication to the Académie des Sciences he described a much improved device for recording the pulse, the sphygmograph, in which the beats were recorded on a smoked plate. Most of his subsequent work was concerned with methods of recording movement: to study the movement of the horse, he used pneumatic sensors on each hoof to record traces on a smoked drum; this device became known as the Marey recording tambour. His attempts to study the wing movements of a bird in flight in the same way met with limited success since the recording system interfered with free movement. Reading in 1878 of Muybridge's work in America using sequence photography to study animal movement, Marey considered the use of photography himself. In 1882 he developed an idea first used by the astronomer Janssen: a camera in which a series of exposures could be made on a circular photographic plate. Marey's "photographic gun" was rifle shaped and could expose twelve pictures in approximately one second on a circular plate. With this device he was able to study wing movements of birds in free flight. The camera was limited in that it could record only a small number of images, and in the summer of 1882 he developed a new camera, when the French government gave him a grant to set up a physiological research station on land provided by the Parisian authorities near the Porte d'Auteuil. The new design used a fixed plate, on which a series of images were recorded through a rotating shutter. Looking rather like the results provided by a modern stroboscope flash device, the images were partially superimposed if the subject was slow moving, or separated if it was fast. His human subjects were dressed all in white and moved against a black background. An alternative was to dress the subject in black, with highly reflective strips and points along limbs and at joints, to produce a graphic record of the relationships of the parts of the body during action. A one-second-sweep timing clock was included in the scene to enable the precise interval between exposures to be assessed. The fixed-plate cameras were used with considerable success, but the number of individual records on each plate was still limited. With the appearance of Eastman's Kodak roll-film camera in France in September 1888, Marey designed a new camera to use the long rolls of paper film. He described the new apparatus to the Académie des Sciences on 8 October 1888, and three weeks later showed a band of images taken with it at the rate of 20 per second. This camera and its subsequent improvements were the first true cinematographic cameras. The arrival of Eastman's celluloid film late in 1889 made Marey's camera even more practical, and for over a decade the Physiological Research Station made hundreds of sequence studies of animals and humans in motion, at rates of up to 100 pictures per second. Marey pioneered the scientific study of movement using film cameras, introducing techniques of time-lapse, frame-by-frame and slow-motion analysis, macro-and micro-cinematography, superimposed timing clocks, studies of airflow using smoke streams, and other methods still in use in the 1990s. Appointed Professor of Natural History at the Collège de France in 1870, he headed the Institut Marey founded in 1898 to continue these studies. After Marey's death in 1904, the research continued under the direction of his associate Lucien Bull, who developed many new techniques, notably ultra-high-speed cinematography.

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See also: Demenÿ, Georges

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SUBJECT AREA: Photography, film and optics

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A cousin of the photographic pioneer J.N. Niepce, he attended the military school of Saumur, graduating in 1827. Niepce de St Victor had wide scientific interests, but came to photography indirectly from experiments he made on fading dyes in military uniforms. He was transferred to the Paris Municipal Guard in 1845 and was able to set up a chemical laboratory to conduct research. From photographic experiments performed in his spare time, Niepce de St Victor devised the first practicable photographic process on glass in 1847. Using albumen derived from the white of eggs as a carrier for silver iodide, he prepared finely detailed negatives which produced positive prints far sharper than those made with the paper negatives of Talbot's calotype process. Exposure times were rather long, however, and the albumen-negative process was soon displaced by the wet-collodion process introduced in 1851, although albumen positives on glass continued to be used for high-quality stereoscopic views and lantern slides. In 1851 Niepce de St Victor described a photographic colour process, and between 1853 and 1855 he developed his famous cousin's bitumen process into a practicable means of producing photographically derived printing plates. He then went on to investigate the use of uranium salts in photography. He presented twenty-six papers to the Académie des Sciences between 1847 and 1862.

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SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering

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Phillips was educated in Paris, at the Ecole Polytechnic and the Ecole des Mines. In 1849 he was awarded a doctorate in mathematical sciences by the University of Paris. He had a varied career in industry, academic and government institutions, rising to be Inspector- General of Mines in 1882.

It was well known that the balance of a watch or chronometer fitted with a simple spiral or helical spring was not isochronous, i.e. the period of the oscillation was not entirely independent of the amplitude. Watch-and chronometer-makers, notably Breguet and Arnold, had devised empirical solutions to the problem by altering the curvature of the end of the balance spring. In 1858 Phillips was encouraged to tackle the problem mathematically, and two years later he published a complete solution for the helical balance spring and a partial solution for the more complex spiral spring. Eleven years later he was able to achieve a complete solution for the spiral spring by altering the curvature of both ends of the spring. Phillips published a series of typical curves that the watch-or chronometer-maker could use to shape the ends of the balance spring.

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SUBJECT AREA: Electricity

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After a scientific training at the Conservatoire des Arts et Métiers, Planté obtained an appointment as a Laboratory Assistant to Becquerel. Later, when he was employed as a chemist in the Parisian electroplating firm of Christofle et Cie, he carried out investigations into polarization in electrical cells, which led to his discovery of the lead-acid accumulator in 1859. This cell, with lead plates in an electrolyte of dilute sulphuric acid, had the characteristics of a storage device for electrical energy. Its performance was improved considerably if it was repeatedly charged and discharged, the active material being formed electrochemically from the lead of the plate itself. At the time of its discovery the Planté cell had little practical application and it was not until satisfactory dynamos were introduced that its commercial exploitation was possible. The cell was improved by Faure and later by Swan and others. The lead-acid cell became considerably important in the early days of electricity supply and later for electric traction and automobile use. The results of Planté's researches were communicated to the Academy of Sciences and published in various scientific periodicals. He devoted the last few years of his life to the study of atmospheric electricity.

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SUBJECT AREA: Electricity

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Following a basic education, Thévénin entered the Ecole Polytechnique in Paris, graduating in 1876. In 1878 he joined the Corps of Telegraph Engineers (which subsequently became the French PTT). There he initially worked on the development of long-distance underground telegraph lines, but he later switched to working on power lines. Appointed a teaching inspector at the Ecole Supérieure in 1882, he became increasingly interested in the problems of measurement in electrical circuits. As a result of studying Kirchoff's Laws, which were essentially derived from Ohm's Law, he developed his now-famous theorem which made it possible to calculate the currents in more complex electrical circuits.

As well as becoming Head of the Bureau des Lignes, up until his death he also found time for teaching other subjects outside the Ecole, including a course in mechanics at the Institut National Agronomique. In 1896 he was appointed Director of the Telegraph Engineering School, then, in 1901, Engineer-in-Chief of the telegraph workshops. He retired in 1914.

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