EINSTEIN IN

COLLABORATION

WITH

GROSSMANN

295

Immediately

after

the

publication

of Einstein and Grossmann

1913

(Doc. 13),

Ein-

stein sent

an offprint

to

Ernst

Mach,

and,

in

an

accompanying letter, acknowledged

his

debt

to

the

latter's "brilliant

investigations

on

the

foundations of

mechanics."[5]

In the

same

letter,

Einstein

mentions several results

demonstrating

that

the

new

theory

of

gravitation

at

least

partially

vindicates Mach's

critique

of Newton's mechanics:

the

dependence

of

the

inertia of

a

body

on

the

proximity

of

surrounding masses,

the

fact

that

the

acceleration of

a mass

shell

induces

an

acceleration of

a

body

it encloses, and

the

creation of

a

Coriolis

field

by a

rotating

mass

shell.

Einstein

presented

these results,

together

with

a

detailed

exposition

of

the

derivation of

the

gravitational

field

equations

and

of

the

heuristics that had

guided

his research, in

a

talk

he

gave

at

a

meeting

of

the

Gesellschaft Deutscher Naturforscher und

Arzte,

held

in

Vienna

in

September

1913.[6]

Like

its

predecessor

for

the static

gravitational field,

the

"Entwurf"

theory predicts

the

deflection

of

light

in

a gravitational

field.[7]

But

in

spite

of Einstein's efforts

to

obtain

empirical

data

on

light

deflection, first

from

already existing eclipse photo-

graphs

and

later

by

involving

himself

in the

organization

of

an

expedition

for

the 1914

total

solar

eclipse,

the

empirical

verification of the

light-bending

effect remained

elu-

sive

until

1919.[8] Similarly,

Einstein's efforts

in

early

summer

1913 to solve the

problem

of

the

perihelion

motion of

Mercury

on

the

basis of

the

"Entwurf"

theory

were

inconclusive,[9]

so

that

the

theory

remained without

empirical

support.

II

From Einstein's research

notes

on

a generalized

theory

of

relativity (Doc.

10)

it

appears

that

initially

his

mastery

of the

mathematical tools

employed

in the

[5]"Ihre

genialen Untersuchungen

über

die

Grundlagen

der Mechanik"

(Einstein to

Ernst

Mach, 25

June

1913

[Vol.

5,

Doc.

448]).

[6]See

Einstein

1913c

(Doc. 17)

for

the

published

version of

the talk.

Einstein later

gave a

similar

but

nontechnical

presentation to

the

Naturforschende Gesellschaft

in

Zurich

(see

Ein-

stein 1914l

[Doc. 27]).

See

also Einstein

and

Besso's

manuscript

on

the

motion of

the

perihelion

of

Mercury

(Doc. 14), [pp.

36-38],

for related calculations

on

the

relativity

of

inertia.

[7]At

the

rim of

the

sun

the

deflection

was

predicted

to be 0.83

seconds of

arc (see,

e.g.,

Einstein 1913d

[Doc. 15],

p.

137),

the

same

value Einstein

had

found

in 1911

(see

Einstein

1911h

[Vol.

3,

Doc.

23],

p.

908).

[8]For

evidence of Einstein's

hope

to

use

already

existing eclipse photographs

to

decide

the

question,

see

Einstein

to

Erwin

Freundlich,

1

September

1911

(Vol.

5,

Doc.

281),

and also

George

Hale

to

Einstein,

8

November

1913

(Vol. 5,

Doc.

483).

For evidence of

his

involvement

in the

expedition

that

was

to

examine

gravitational light

deflection

during

the

solar

eclipse

of

21 August 1914, see

Einstein

to

Heinrich

Zangger,

ca.

20

January

1914

(Vol.

5,

Doc.

507),

and

Einstein

to

Erwin

Freundlich,

7

December

1913

(Vol. 5,

Doc.

492),

as

well

as

his

later

correspondence

with

Freundlich.

See

also Earman and

Glymour

1980a for

a

historical

discussion.

[9]See Einstein

and

Besso's

manuscript

on

the

motion of

the

perihelion

of

Mercury (Doc.

14) and,

for further

discussion, the

editorial

note,

"The Einstein-Besso

Manuscript

on

the

Motion of

the

Perihelion of

Mercury,"

pp.

344-359.