1.  Timothy Hopkins.  1932.  John Hopkins of Cambridge, Massachusetts, 1634, and Some of His Descendants.  Stanford Univ. Press, Stanford, CA.

2.  1870 Census Images (online at Genealogy.com, Image #4 of 121; online at Ancestry.com, Image #300 of 417):  Sacramento (Ward 4), Sacramento Co., CA, p. 320B, PN 4, enumerated ca. 9 Jun 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):

1870:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	9	10	11	12	15	19
27	36	Hopkins Mark	54	M	W	Treasr R R Co	9150	8,655,780	New York				/
		_______ Mary F	48	F	W	Keeps House			"   "
		Nolan Timmy N	9	M	W	attends school			Maine			/
		Ah Sing	25	M	C	domestic			China	/	/

3.  1880 Census Every-Name-Index/Images (online at Ancestry.com, Image #6-7 of 22):  California [St.], San Francisco, San Francisco Co., CA, Roll T9_74, pp. 701B-702C, PN 6-7, SD 1, ED 55, enumerated 2 Jun 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

8

9

11

13

24

25

26

*

42

48

Hopkins M F

W

F

52

/

Keeping house

NY

CT

MA

_______ Timothy

W

M

21

adopted son

/

At home

Calif

Calif

Calif

Crittenden May

W

F

17

Niece

/

At home

MO

NY

NY

[plus nine servants]

*California

Mary adopted Timothy, her housekeeper's son, as an adult, after the death of her husband in 1878.  Timothy was born in Maine, not CA, and his parents were born in Ireland, not CA. Timothy later married Mary's niece, May CRITTENDEN.

4.  1890 Census:  the 1890 Census Population Schedules were destroyed.

5.  1900 Census Index/Microfilm (online at Genealogy.com):  Third Township, San Mateo Co., CA, p. 229A, SD 2, ED 40, SN 4, enumeratd 8 Jun 1900 (extracted by Diana Gale Matthiesen):

1900:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	19	20	21	22	23	24	25	26	27	28
60	60	Hopkins Timothy	Head	W	M	May 1858	42	M	17			Maine	Maine	Maine	Capitalist	0		Y	Y	Y	O	F	F	34
		_______ May	Wife	W	F	Mar 1864	36	M	17	1	1	St. Louis	St. Louis	Maine				Y	Y	Y
		_______ Lydia	Dau.	W	F	Mar 1887	13	S				Calif.	Maine	St. Louise (sic)	At School	0	10	Y	Y	Y

There are a great many anomalies in this record.  Makes you wonder if the daughter wasn't the informant.

6.  1910 Census Index/Images (online at Ancestry.com, Image #22 of 25):  1950 Washington Street, San Francisco City, Assembly Dist. No. 44, Pct. No. 6, San Francisco Co., CA, Roll T624_101 (Part 2), p. 88B, SN 11B, SD 4, ED 269, enumerated 29 Apr 1910, official enumeration date 15 Apr 1910 (extracted by Diana Gale Matthiesen):

1910:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
		1	2	3	4	5	6	7	8	9	10	11	12	13	14	17	18	23	24	25	26	28
*	1950	136	191	Hopkins Timothy	Head	M	W	51	M1	28			ME	NY	NY	Eng	Own Income	Y	Y		R	H
				_______ Mary K	Wife	F	W	40	M1	28	3	1	MO	MA	NY	Eng	Own Income	Y	Y
				_______ Lyda K	Dau	F	W	23	S				CA	ME	MO	Eng	none	Y	Y	Y
				[Plus five servants.]
*Washington Street

7.  1920 Census Index/Images (online at Ancestry.com):  can't find.

8a.  1930 Census Index/Images (online at Ancestry.com):  can't find Timothy or Mary.

8b.  1930 Census Index/Images (online at Ancestry.com, Image #10 of 26):  415 South Ellsworth, San Mateo City (Pcts. 24 & 25), San Mateo Twp., San Mateo Co., CA, Roll 216, p. 226B, SN 5B, ED 41-32, SD 10, enumerated 8/9 Apr 1930, official enumeration date 1 Apr 1930 (extracted by Diana Gale Matthiesen):

1930:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	10	11	12	13	14	16	17	18	19	20	24	25	26	27	28
*	415	115	130	Hopkins Lydia	Head	R	40.00	N	F	W	43	S	N	Y	CA	ME	MO	Y	Business	Gift Shop	O	Y
*South Ellsworth

9.  Harold Clarke Durrell.  1936.  "Memoirs of Deceased Members of the New England Historic Genealogical Society." New England Historical and Genealogical Register 90(April): 167-194.  On p. 182:

TIMOTHY HOPKINS, of Menlo Park, Calif., adopted son of Mark and Mary Frances (Sherwood) Hopkins, elected a resident member 6 May 1896 and made a life member 18 May 1896, was born at Hallowell, Maine, 2 March 1859, the son of Patrick and Catherine (Fallon) Nolan, and died in San Francisco, Calif., 1 January 1936. His father, Patrick Nolan, born at Glenmore, co. Mayo, Ireland, in 1829, came to New England in 1852, settled at Winthrop, Maine, where he found employment in an oilcloth shop, and married Catherine Fallon.  In May 1862 he left home for California to seek better fortune in the gold fields.  However, he secured work in San Francisco and sent East for his family, but he was accidentally drowned on the day that they sailed form New York. Mrs. Nolan, who later married a second time and moved to St. Louis, Mo., found work in the family of Mark Hopkins, the railroad magnate, and in a short time Timothy, now three years of age, was made a member of the family.  On the death of Mark Hopkins in 1878, he was legally adopted by the widow, who married secondly, in 1887, Edward F. Searles, and died in 1891. He was educated in the public schools of California and, for a few years, in schools in New England.  He intended to enter Harvard College, but ill health prevented him from doing so. He entered the employ of the Central Pacific Railroad, served apprenticeship in various departments, and was a director and treasurer of the company from 1883 to 1892.  When the Southern Pacific Railroad Company was organized in 1885, he served as its first treasurer and as a director, positions which he held until 1892, when he resigned to have more time in which to direct his own affairs. Presented by his mother with a wedding gift of a huge estate at Menlo Park, he developed it into a successful flower business, raising acres of violets and chrysanthemums for the San Francisco trade. Deeply interested in the genealogy of his adoptive family, he published "The Kelloggs in the Old World and the New," 3 vols., 1903, and "John Hopkins and Some of His Descendants," 1932. He gave generously of his money to the Convalescent Home for Children at Palo Alto, Calif., and he built and gave to Stanford University the Hopkins Marine Station at Pacific Grove, Calif.  He also made possible the unrivalled collection of early railroad history owned by Stanford University. He was president of the Southern Pacific Milling Company, a director of the Wells Fargo Bank and Union Trust Company, a life member of the board of trustees of Leland Stanford, Jr., University, and had served as a director of the Pacific Telephone and Telegraph Company, and the Union Ice Company.  He was a life member of the University Club and a member of the higher order of Masonry. He married in New York City, 28 November 1882, Mary Kellogg Crittenden, born in St. Louis, Mo., daughter of Hiram and Lydia (Sherwood) Crittenden, who, with one daughter, Lydia Kellogg Hopkins of San Mateo, Calif., survives him.

Timothy NOLAN was not the adopted son of "Mark and Mary Frances (Sherwood) Hopkins"; he was adopted as an adult, after the death of Mark HOPKINS in 1878, by Mark's widow, Mary Frances (SHERWOOD) HOPKINS, who ultimately disinherited him.