IMGr8

Ernst Mach

A.    Orni Suggcstions (i860-1864)

1.    Microphotography (1860)

2.    Pcrccptual scnsidvitics of thc mcntally iii (1861)

3.    Why gcomctrically similar figurcs arc alsooptically similar (i86os)

B.    Expcrimcntal Work (1860-1864)

1.    Doppler Theory (1860)

2.    Fcchncr’s logarithmic law (1860)

3.    Construction of an improvcd blood pressure mcasuring dcvicc (1862)

4.    Molccular bchavior of liquids (1862)

5.    Attempts to improvc and go beyond I Iclmholtz’s work on acous-tics and car structurc (1863-1864)

1 i er o photography In Machs own words:

About 17 ycars ago [ 1859-1860] while still a student I discusscd a projcct to develop microphotography [micro sized photographs, not microscopc photography] with Herr Aucr, who at that time was dircctor of thc State publishing housc, bul hc rcjcctcd it as impractical. . . . under particular circumstanccs microphotography scems to be a valuablc tool for thc spread of literary materiał and as superior to printing as printing is to handwrit-ing. f cannot object to thc complaint of lack of practical cxpcricncc in tliis field, and that this projcct cannot be immcdiatcly put into practicc, bccausc of immense difficulties which arc still present. But I cannot rcjcct thc idea in principle, sińce it has dcveloped from my own undcniablc nceds, of having had a very limited library while having to work on a farm.⁸

It seems elear that Mach anticipated both thc need for and the possi-bility of microfilming. We do not know if cither his orał suggestion or his 1876 articlc contributcd to or hclped hurry thc dcvclopmcnt of microphotography as applied to rcading materiał; nonethcless, bis early support and efforts dcserve to be rcscucd from oblivion. He was clcarły a pioncer and well ahead of his time.

Sense Perccptions of the Mcntally lll

Mach suggested that therc might be vałue in cxamining thc perceptual sensirivities of mental asylum patients. He first proposcd this beforc a group of collcagucs in 1861 and in the following ycar beforc a gather-

Young Sctcniist

ing of thc Austrian Socicty of Doctorsź* Unfortunately, his idea madc linie impression at thc time.

Gcomctrically and Optically Similar Figura

Another vcrbal foray was cven less succcssful—wcrc that possiblc— though thc ideas presented appear today to have bccn a rcmarkablc anticipation of somc of thc basie notions of Gcstalt psychology. Mach rcmcmbcrcd: "Some forty ycars ago, in a socicty of physicists and phy-siologists I proposed for discussion thc qucstion, why gcomctrically similar figurcs wcrc also optically similar. 1 remember quitc wcll thc attitudc taken with regard to this qucstion, which was accountcd not only supcrfluous, but cvcn ludicrous. Ncvcrthclcss, I am now as strongly convinccd as I was then that this qucstion involvcs thc wholc problem of form-vision.” ¹⁰

We mny add that Mach did not drop thc issue, but soon began to writc articlcs on it. Indced, many of his latcr books includcd chaptcrs or at least groups of paragraphs on this subjcct and on rclaicd prób-lcms.

The Doppler Theory

Christian Doppler (1803-1853) notieed in 18-41 that thc frcqucncy of sound waves as measured by pitch changcd as the source approached or rcccded from the listener. Two ycars latcr he extcnded this obscrva-tion to light wavcs as measured by changcs in color. By 1845 he had generalized what might be callcd thc Doppler theory to all wave motions from moving sources. In 1845 thc Dutch meteorologist Buys Ballot had also conductcd some railway cxperimcnts which sccmcd to confirm thc Doppler eflect, at least with respcct to sound.

Doppler’s colleague, howcver, thc ecccntric Professor losef Pctzval, attackcd thc Doppler theory on theoretical grounds from the standpoint of his own “Law of the Conservation of the Period of Oscillation." He denied the rcality of the Doppler effect. Professor Anders Angstróm of Uppsala in Sweden also elaimed that he was unablc to mcasurc thc Doppler cfTcct with respcct to light.

Shortly after Mach receivcd his doctorate, Von Ettinghausen cn-couraged him to construct an apparatus that could help settle the Doppler controvcrsy. The young scicntisfs first attempt tailcd. but a

17