[R] reading header in txt file and making histogram

[bamboohydraulics]

Dear all

I am a BEGINNER and have R on my Mac. I saved my excel file as .txt file, I
have just one column with first row as the column name. My file when read by
R looks like this. After reading the table I try to make a histogram by 
hist(dbh), it says  object dbh not found. What am I doing wrong? thanks
      dbh
1   11.53
2   16.05
3    7.36
4   16.05
5    8.66
6   12.74
7   22.93
8    7.55
9    5.10
10  21.34
11   0.32
12   9.71
13   0.00
14  15.92
15  11.85
16  14.43
17   4.59
18  14.43
19   7.99
20   2.61
21  23.69
22   6.05
23   9.87
24   4.90
25   3.18
26   3.82
27   0.00
28  12.10
29   5.22
30   6.37
31   6.50
32  10.83
33   3.63
34   2.93
35   3.60
36   5.89
37   3.63
38   2.55
39   2.96
40   3.69
41   5.57
42   0.00
43   7.07
44   5.48
45   9.55
46   3.44
47   0.00
48   0.00
49   3.69
50   2.48
51   3.38
52   2.64
53  12.10
54   3.34
55   0.00
56   4.52
57   6.59
58   9.65
59   9.01
60  12.93
61   0.00
62   4.24
63   9.75
64   4.39
65   2.90
66   6.85
67   9.08
68   5.54
69   6.02
70   7.64
71   6.85
72   0.00
73   3.12
74   6.75
75   4.24
76   2.32
77   2.58
78   2.55
79   8.60
80   0.00
81   0.32
82   2.23
83   3.98
84   6.05
85   7.64
86   3.03
87   0.00
88   9.27
89   0.00
90   0.00
91   3.92
92   0.00
93  20.54
94   8.41
95   0.00
96   2.10
97   0.00
98   0.00
99  13.79
100  5.22
101  9.43
102  6.31
103  4.11
104  0.00
105  0.00
106  6.15
107  3.41
108 14.01
109 15.67
110 17.20
111 20.00
112 11.43
113 10.35
114 10.29
115 13.18
116 10.61
117  0.00
118  0.32
119  0.00
120  7.01
121  1.97
122  4.52
123 19.14
124  3.50
125  2.99
126  3.18
127  1.82
128  3.18
129  6.02
130  4.04
131  2.61
132  2.48
133  2.71
134  2.68
135  1.82
136  2.52
137  6.72
138  2.61
139  2.74
140  3.15
141  3.25
142  3.22
143  3.44
144  4.01
145  4.97
146  6.15
147  9.62
148  2.87
149  5.83
150 17.90
151  3.18
152  3.54
153  2.99
154  4.62
155  6.85
156  0.00
157  5.83
158  4.49
159  2.74
160  6.82
161  6.82
162  4.94
163  5.83
164  6.02
165  0.96

--
View this message in context: http://r.789695.n4.nabble.com/reading-header-in-txt-file-and-making-histogram-tp4504813p4504813.html
Sent from the R help mailing list archive at Nabble.com.