Converting analog 10-bit thermistor reading (MCP3008) to temperature
I am just suggesting you to try this, consider the below circuit







simulate this circuit &ndash; Schematic created using CircuitLab

For example if you read 1.57 volts

from this you can calculate the resistance of the thermistor, 

VR2(voltage at resistor R2) = 3.3 * R2/(R1+R2)

in this expression VR2 and R2 is know so you can compute the value of R1.

R1 = ( (3.3 * R2) - (VR2 * R2 ) ) / VR2

for this example the R1 = 1101 OHMS

From this value you can find the temperature by creating a look up table as in the datasheet you included in the link.