type
  TValues = Class
    dtTime : TDateTime;
    rForce,
    rTemperature,
    rHumidity : Real;
  End;


var
  Form1: TForm1;
  threadList1 : TThreadList;

...

procedure TForm1.FormCreate(Sender: TObject);
begin
  threadList1 := TThreadList.Create;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if (mythreadRunning = FALSE) then
  begin
    mythreadRunning:= TRUE;
    secondProcess := TMyThread.Create(True); { Create suspended--secondProcess does not run yet. }
    secondProcess.FreeOnTerminate := True; { You do not need to clean up after termination. }
    secondProcess.Priority := tpNormal; // Set the priority to lower than normal.
    secondProcess.Resume; { Now run the thread. }
  end
  else
    MessageDlg('This thread is still running. You are going to hurt yourself!',
      mtInformation, [mbOk], 0);
end;


procedure TMyThread.Execute;
var
  Values: TValues;
begin
  while(True) do
  begin
    if (Terminated) then
    begin
      mythreadRunning:= FALSE;
      exit;
    end;
    globalCount:= globalCount + 1;
    Values := TValues.Create;
    Values.dtTime := now;
    Values.rForce := globalCount;
    Values.rTemperature := globalCount/3;
    Values.rHumidity := globalCount/7;
    threadList1.Add(Values);
    Sleep(10);
  end;
  mythreadRunning:= FALSE;
end;