DOC. 14

EINSTEIN AND BESSO MANUSCRIPT

423

[p.

31] (Besso)

[137][P.

31]

is

the

verso

of

[p.

30].

Besso

presumably

used the back of

[p.

30]

after Einstein

sent

him

the

manuscript

in 1914

(see

the editorial

note,

"The Einstein-Besso

Manuscript

on

the

Motion of the Perihelion of

Mercury," sec. III).

[138]The

key

to understanding

[p. 31]

is

the

reference "Newcomb S. 127"

given

for

the "Präzes-

sionsconstante P." The reference

is

to

Newcomb 1895,

p.

127. This book offers

a

detailed

discussion of

the

analysis

carried

out

by

Newcomb in

constructing

new

tables

for

the

four inner

planets published

that

same

year

(for

a

discussion

of

this

book,

see

Roseveare

1982, pp.

44-

67).

The

project

outlined

on

[p.

31]

under the

heading

"Plan"

is to

make certain corrections

to

Newcomb's

analysis on

the basis of the "Entwurf"

theory.

More

specifically,

the

project

is to

find

the corrections

to

the values for solar

parallax

and for the

planetary masses coming

from

two

effects

predicted

by

the "Entwurf"

theory,

namely,

the

bending

of

light

and the

motion of

nodes caused

by

the rotation of the

sun

(detailed

calculations for the latter effect

can

be

found

on

[pp.

45-49];

see

the editorial

note,

"The Einstein-Besso

Manuscript

on

the Motion of the

Perihelion of

Mercury," sec.

II.3).

[139]As

part

of the

project

outlined above

(see

note

138),

the

question

is

raised whether the

bending

of

light predicted by

the "Entwurf"

theory can

be

used

to

explain

the

discrepancy

between the results of

two

related methods

to

determine solar

parallax

from observations of

transits of

Venus.

The different methods

to

determine solar

parallax

mentioned

on [p. 31]

and

the results that

are given

can

all be

found

in

a

table

on p.

157

of

Newcomb 1895

under the header:

"Results

of

determinations

of

the

solar

parallax arranged

in

the order

of

magnitude"

(this

table

is

reproduced

and discussed

in

Roseveare

1982,

pp.

57-63).

The table

gives

nine different

results,

five

of

which-with

rounded-off

numbers-can

be found

on

[p. 31].

The relevant entries

are,

in

the order

in

which

they

appear

on [p. 31]:

8.794" ± .018"

(from

observations of

contacts

during

transits of

Venus),

8.857" ± .023"

(from

measurements

of

the

distance of

Venus

from the

sun's

center

during transits),

8.793"

±

.0046"

(from

Pulkowa determinations of

the constant

of

aberration),

8.806" ± .0056"

(from

determinations of

the constant

of aberration made elsewhere

than

at

Pulkowa),

8.759" ± .010"

(from

the

mass

of

the Earth

resulting

from the secular

variations

of the orbits of the four inner

planets).

Contacts

are

the

moments when Venus

touches the rim

of the

sun during

a

transit. Pulkowa

or

Pulkovo

is

an

observatory

near

St.

Petersburg.

From

the relative

weights

Newcomb

assigned

to

the nine results listed

in his table, it is

clear that

he

considered the method based

on

the determination of the

constant

of aberration

to be

the

most

reliable method.